Class 12 | Physics | Chapter Wise Derivation List - JEE PDF Download

 Page 1


Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 1 
 
 
Electrostatics- 
1. Derive an expression for the electric field at a point on the axial position of an 
electric dipole. 
2. Derive an expression for the electric field at a point on the equatorial position of an 
electric dipole. 
3. Describe the Principle, construction and working of Van de Graff generator. 
4. Derive an expression for the energy stored in a capacitor. Show that whenever two 
conductors share charges by bringing them into electrical contact, there is a loss of 
energy. 
5. Derive an expression for the effective capacitance when capacitors are connected 
in (a) series and (b) parallel 
6. Explain the principle of a capacitor and derive an expression for the capacitance of 
a parallel plate capacitor. 
7.  State Gauss theorem and apply it to find the electric field at a point due to (a) a 
line of charge (b) A plane sheet of charge (c) A Charged spherical conducting shell 
8. State Coulomb's law and express it in vector form. Derive it using Gauss theorem. 
9. Derive an expression for the torque on an electric dipole in a uniform electric field. 
10. Derive an expression for the work done in rotating an electric dipole in a uniform 
electric field 
11. Derive an expression for the energy stored (Potential Energy) in a dipole in a 
uniform electric field. 
12. Derive an expression for the electrostatic potential energy of a system of point 
charges 
13. Derive an expression for the capacitance of a parallel plate capacitor with (a) a 
dielectric slab (b) a metallic plate in between the plates of the capacitor. 
14. Define electric potential at a point. Derive an expression for the electric potential at 
a point due to (a) a point charge (b) a system of point charges (c) a dipole. 
15. Show that the work done in an electric field is independent of path. 
16. What are dielectrics? Distinguish polar and nonpolar dielectrics. Define the term 
Polarization vector. 
Current Electricity- 
1. Define drift velocity and derive an expression for it. 
2. Derive the expression I=nAev
d
 
3. Deduce Ohm's law from elementary ideas and hence write an expression for 
resistance and resistivity. 
4. Derive an expression for conductivity in terms of mobility 
5. Explain the color coding of carbon resistors. 
6. Derive an expression for the current in a circuit with external resistance R when (a) 
n identical cells of emf E and internal resistance r are connected in series (b) m 
identical cells are connected in parallel 
7. State and explain Kirchhoff’s laws. 
Page 2


Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 1 
 
 
Electrostatics- 
1. Derive an expression for the electric field at a point on the axial position of an 
electric dipole. 
2. Derive an expression for the electric field at a point on the equatorial position of an 
electric dipole. 
3. Describe the Principle, construction and working of Van de Graff generator. 
4. Derive an expression for the energy stored in a capacitor. Show that whenever two 
conductors share charges by bringing them into electrical contact, there is a loss of 
energy. 
5. Derive an expression for the effective capacitance when capacitors are connected 
in (a) series and (b) parallel 
6. Explain the principle of a capacitor and derive an expression for the capacitance of 
a parallel plate capacitor. 
7.  State Gauss theorem and apply it to find the electric field at a point due to (a) a 
line of charge (b) A plane sheet of charge (c) A Charged spherical conducting shell 
8. State Coulomb's law and express it in vector form. Derive it using Gauss theorem. 
9. Derive an expression for the torque on an electric dipole in a uniform electric field. 
10. Derive an expression for the work done in rotating an electric dipole in a uniform 
electric field 
11. Derive an expression for the energy stored (Potential Energy) in a dipole in a 
uniform electric field. 
12. Derive an expression for the electrostatic potential energy of a system of point 
charges 
13. Derive an expression for the capacitance of a parallel plate capacitor with (a) a 
dielectric slab (b) a metallic plate in between the plates of the capacitor. 
14. Define electric potential at a point. Derive an expression for the electric potential at 
a point due to (a) a point charge (b) a system of point charges (c) a dipole. 
15. Show that the work done in an electric field is independent of path. 
16. What are dielectrics? Distinguish polar and nonpolar dielectrics. Define the term 
Polarization vector. 
Current Electricity- 
1. Define drift velocity and derive an expression for it. 
2. Derive the expression I=nAev
d
 
3. Deduce Ohm's law from elementary ideas and hence write an expression for 
resistance and resistivity. 
4. Derive an expression for conductivity in terms of mobility 
5. Explain the color coding of carbon resistors. 
6. Derive an expression for the current in a circuit with external resistance R when (a) 
n identical cells of emf E and internal resistance r are connected in series (b) m 
identical cells are connected in parallel 
7. State and explain Kirchhoff’s laws. 
Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 2 
 
 
8. State and explain the principle of Wheat Stone's principle. Deduce it using 
Kirchhoff’s laws. 
9. Describe how you will determine the resistance of a given wire using Meter 
Bridge. 
10. Explain the principle of a potentiometer. Describe how will you determine (a) the 
ratio of emfs of two primary cells using potentiometer. (b) The internal resistance 
of a primary cell using potentiometer. 
11. Explain the variation of resistance and resistivity with temperature and hence 
define temperature coefficient of resistance and resistivity. 
Magnetic Effect of Current 
1. State Biot- Savart law and apply it to find the magnetic field due to a circular loop 
carrying current at a point (a) at its centre (b) on the axis 
2. State Ampere's circuital law and apply it to find the magnetic field (a) inside a 
current carrying solenoid (b) inside a current carrying toroid 
3. Apply Ampere's circuital law to determine the magnetic field at a point due to a 
long straight current carrying conductor. 
4. Derive an expression for the force on a current carrying conductor in a uniform 
magnetic field 
5. Derive an expression for the force between long straight conductors carrying 
current and hence define 1 ampere. 
6.  Derive an expression for the torque on a current carrying loop in a uniform 
magnetic field. 
7. Describe the principle construction and working of a Moving coil galvanometer. 
8. Describe the conversion of a moving coil galvanometer into (a) Ammeter (b) 
Voltmeter 
9. What is radial magnetic field? What is its importance in a moving coil 
galvanometer? How is a radial magnetic field realized in moving coil 
galvanometers? 
10. Describe the principle construction and working of a cyclotron. Explain why an 
electron cannot be accelerated using a cyclotron. 
11. Describe the motion of a charged particle in a magnetic field when it enters the 
field (a) perpendicular to the field lines (b) obliquely making and angle T with the 
field lines 
12. Derive an expression for the magnetic dipole moment of a revolving electron and 
hence define Bohr magneton. 
Electromagnetic Induction (EMI)- 
1. State and Explain Faraday's laws of electromagnetic induction.() 
2. State Lenz' Law and show that it is in accordance with the law of conservation of 
energy. 
3. Use Lenz' law to find the direction of induced emf in a coil when (a) a north pole is 
brought towards the coil (b) north pole taken away from the coil (c) A south pole is 
Page 3


Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 1 
 
 
Electrostatics- 
1. Derive an expression for the electric field at a point on the axial position of an 
electric dipole. 
2. Derive an expression for the electric field at a point on the equatorial position of an 
electric dipole. 
3. Describe the Principle, construction and working of Van de Graff generator. 
4. Derive an expression for the energy stored in a capacitor. Show that whenever two 
conductors share charges by bringing them into electrical contact, there is a loss of 
energy. 
5. Derive an expression for the effective capacitance when capacitors are connected 
in (a) series and (b) parallel 
6. Explain the principle of a capacitor and derive an expression for the capacitance of 
a parallel plate capacitor. 
7.  State Gauss theorem and apply it to find the electric field at a point due to (a) a 
line of charge (b) A plane sheet of charge (c) A Charged spherical conducting shell 
8. State Coulomb's law and express it in vector form. Derive it using Gauss theorem. 
9. Derive an expression for the torque on an electric dipole in a uniform electric field. 
10. Derive an expression for the work done in rotating an electric dipole in a uniform 
electric field 
11. Derive an expression for the energy stored (Potential Energy) in a dipole in a 
uniform electric field. 
12. Derive an expression for the electrostatic potential energy of a system of point 
charges 
13. Derive an expression for the capacitance of a parallel plate capacitor with (a) a 
dielectric slab (b) a metallic plate in between the plates of the capacitor. 
14. Define electric potential at a point. Derive an expression for the electric potential at 
a point due to (a) a point charge (b) a system of point charges (c) a dipole. 
15. Show that the work done in an electric field is independent of path. 
16. What are dielectrics? Distinguish polar and nonpolar dielectrics. Define the term 
Polarization vector. 
Current Electricity- 
1. Define drift velocity and derive an expression for it. 
2. Derive the expression I=nAev
d
 
3. Deduce Ohm's law from elementary ideas and hence write an expression for 
resistance and resistivity. 
4. Derive an expression for conductivity in terms of mobility 
5. Explain the color coding of carbon resistors. 
6. Derive an expression for the current in a circuit with external resistance R when (a) 
n identical cells of emf E and internal resistance r are connected in series (b) m 
identical cells are connected in parallel 
7. State and explain Kirchhoff’s laws. 
Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 2 
 
 
8. State and explain the principle of Wheat Stone's principle. Deduce it using 
Kirchhoff’s laws. 
9. Describe how you will determine the resistance of a given wire using Meter 
Bridge. 
10. Explain the principle of a potentiometer. Describe how will you determine (a) the 
ratio of emfs of two primary cells using potentiometer. (b) The internal resistance 
of a primary cell using potentiometer. 
11. Explain the variation of resistance and resistivity with temperature and hence 
define temperature coefficient of resistance and resistivity. 
Magnetic Effect of Current 
1. State Biot- Savart law and apply it to find the magnetic field due to a circular loop 
carrying current at a point (a) at its centre (b) on the axis 
2. State Ampere's circuital law and apply it to find the magnetic field (a) inside a 
current carrying solenoid (b) inside a current carrying toroid 
3. Apply Ampere's circuital law to determine the magnetic field at a point due to a 
long straight current carrying conductor. 
4. Derive an expression for the force on a current carrying conductor in a uniform 
magnetic field 
5. Derive an expression for the force between long straight conductors carrying 
current and hence define 1 ampere. 
6.  Derive an expression for the torque on a current carrying loop in a uniform 
magnetic field. 
7. Describe the principle construction and working of a Moving coil galvanometer. 
8. Describe the conversion of a moving coil galvanometer into (a) Ammeter (b) 
Voltmeter 
9. What is radial magnetic field? What is its importance in a moving coil 
galvanometer? How is a radial magnetic field realized in moving coil 
galvanometers? 
10. Describe the principle construction and working of a cyclotron. Explain why an 
electron cannot be accelerated using a cyclotron. 
11. Describe the motion of a charged particle in a magnetic field when it enters the 
field (a) perpendicular to the field lines (b) obliquely making and angle T with the 
field lines 
12. Derive an expression for the magnetic dipole moment of a revolving electron and 
hence define Bohr magneton. 
Electromagnetic Induction (EMI)- 
1. State and Explain Faraday's laws of electromagnetic induction.() 
2. State Lenz' Law and show that it is in accordance with the law of conservation of 
energy. 
3. Use Lenz' law to find the direction of induced emf in a coil when (a) a north pole is 
brought towards the coil (b) north pole taken away from the coil (c) A south pole is 
Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 3 
 
 
brought towards the coil and (d) a south pole is taken away from the coil, Draw 
illustrations in each case. 
4. What is motional emf. Deduce an expression for it. State Fleming's right hand rule 
to find the direction of induced emf. 
5. What are eddy currents? Describe the applications of eddy currents. 
6. Explain the working of (a) Electromagnetic Brakes (b) Induction Furnace 
7. Which physical quantity is called the INERTIA OF ELECTRICITY? Why is its 
called so?  
8. Define self induction and self inductance. What is its unit? Write its dimensions. 
9. Derive an expression for the self inductance of a long solenoid. 
10. Explain the phenomenon of mutual induction and define mutual inductance. Write 
the unit and dimensions of mutual inductance. 
11. What are the factors affecting mutual inductance of a pair of coils? Define 
coefficient of coupling. 
12. Describe the various methods of producing induced emf. Derive an expression for 
the instantaneous emf induced in a coil rotated in a magnetic field. 
13. What is displacement current? Explain its need. 
Alternative Current- 
1. Describe the principle construction and working of an AC generator. Draw neat 
labeled diagram 
2. Define mean value of AC(over a half cycle) and derive an expression for it. 
3. Define RMS value of AC and derive an expression for it. () 
4. Show that the average value of AC over a complete cycle is zero. 
5. Show that the current and voltage are in phase in an ac circuit containing resistance 
only. 
6. Deduce the phase relationship between current and voltage in an ac circuit 
containing inductor only. 
7. Deduce the phase relationship between current and voltage in an ac circuit 
containing capacitor only. 
8. Draw the phasor diagram showing voltage and current in LCR series circuit and 
derive an expression for the impedance 
9. What do you mean by resonance in Series LCR circuit? Derive an expression for 
the frequency of resonance in LCR circuit. 
10. Distinguish between resistance, reactance and impedance. 
11. Define quality factor (Q factor) of resonance and derive an expression for it. 
12. Describe the mechanism of electromagnetic oscillations in LC circuit and write 
expression for the frequency of oscillations produced. 
13. Derive an expression for the average power in an ac circuit. 
14. Define power factor. Deduce expression for it and explain wattless current? 
15. Describe the principle construction theory and working of a transformer. 
16. Describe the various losses in a transformer and explain how the losses can be 
minimized. 
Page 4


Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 1 
 
 
Electrostatics- 
1. Derive an expression for the electric field at a point on the axial position of an 
electric dipole. 
2. Derive an expression for the electric field at a point on the equatorial position of an 
electric dipole. 
3. Describe the Principle, construction and working of Van de Graff generator. 
4. Derive an expression for the energy stored in a capacitor. Show that whenever two 
conductors share charges by bringing them into electrical contact, there is a loss of 
energy. 
5. Derive an expression for the effective capacitance when capacitors are connected 
in (a) series and (b) parallel 
6. Explain the principle of a capacitor and derive an expression for the capacitance of 
a parallel plate capacitor. 
7.  State Gauss theorem and apply it to find the electric field at a point due to (a) a 
line of charge (b) A plane sheet of charge (c) A Charged spherical conducting shell 
8. State Coulomb's law and express it in vector form. Derive it using Gauss theorem. 
9. Derive an expression for the torque on an electric dipole in a uniform electric field. 
10. Derive an expression for the work done in rotating an electric dipole in a uniform 
electric field 
11. Derive an expression for the energy stored (Potential Energy) in a dipole in a 
uniform electric field. 
12. Derive an expression for the electrostatic potential energy of a system of point 
charges 
13. Derive an expression for the capacitance of a parallel plate capacitor with (a) a 
dielectric slab (b) a metallic plate in between the plates of the capacitor. 
14. Define electric potential at a point. Derive an expression for the electric potential at 
a point due to (a) a point charge (b) a system of point charges (c) a dipole. 
15. Show that the work done in an electric field is independent of path. 
16. What are dielectrics? Distinguish polar and nonpolar dielectrics. Define the term 
Polarization vector. 
Current Electricity- 
1. Define drift velocity and derive an expression for it. 
2. Derive the expression I=nAev
d
 
3. Deduce Ohm's law from elementary ideas and hence write an expression for 
resistance and resistivity. 
4. Derive an expression for conductivity in terms of mobility 
5. Explain the color coding of carbon resistors. 
6. Derive an expression for the current in a circuit with external resistance R when (a) 
n identical cells of emf E and internal resistance r are connected in series (b) m 
identical cells are connected in parallel 
7. State and explain Kirchhoff’s laws. 
Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 2 
 
 
8. State and explain the principle of Wheat Stone's principle. Deduce it using 
Kirchhoff’s laws. 
9. Describe how you will determine the resistance of a given wire using Meter 
Bridge. 
10. Explain the principle of a potentiometer. Describe how will you determine (a) the 
ratio of emfs of two primary cells using potentiometer. (b) The internal resistance 
of a primary cell using potentiometer. 
11. Explain the variation of resistance and resistivity with temperature and hence 
define temperature coefficient of resistance and resistivity. 
Magnetic Effect of Current 
1. State Biot- Savart law and apply it to find the magnetic field due to a circular loop 
carrying current at a point (a) at its centre (b) on the axis 
2. State Ampere's circuital law and apply it to find the magnetic field (a) inside a 
current carrying solenoid (b) inside a current carrying toroid 
3. Apply Ampere's circuital law to determine the magnetic field at a point due to a 
long straight current carrying conductor. 
4. Derive an expression for the force on a current carrying conductor in a uniform 
magnetic field 
5. Derive an expression for the force between long straight conductors carrying 
current and hence define 1 ampere. 
6.  Derive an expression for the torque on a current carrying loop in a uniform 
magnetic field. 
7. Describe the principle construction and working of a Moving coil galvanometer. 
8. Describe the conversion of a moving coil galvanometer into (a) Ammeter (b) 
Voltmeter 
9. What is radial magnetic field? What is its importance in a moving coil 
galvanometer? How is a radial magnetic field realized in moving coil 
galvanometers? 
10. Describe the principle construction and working of a cyclotron. Explain why an 
electron cannot be accelerated using a cyclotron. 
11. Describe the motion of a charged particle in a magnetic field when it enters the 
field (a) perpendicular to the field lines (b) obliquely making and angle T with the 
field lines 
12. Derive an expression for the magnetic dipole moment of a revolving electron and 
hence define Bohr magneton. 
Electromagnetic Induction (EMI)- 
1. State and Explain Faraday's laws of electromagnetic induction.() 
2. State Lenz' Law and show that it is in accordance with the law of conservation of 
energy. 
3. Use Lenz' law to find the direction of induced emf in a coil when (a) a north pole is 
brought towards the coil (b) north pole taken away from the coil (c) A south pole is 
Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 3 
 
 
brought towards the coil and (d) a south pole is taken away from the coil, Draw 
illustrations in each case. 
4. What is motional emf. Deduce an expression for it. State Fleming's right hand rule 
to find the direction of induced emf. 
5. What are eddy currents? Describe the applications of eddy currents. 
6. Explain the working of (a) Electromagnetic Brakes (b) Induction Furnace 
7. Which physical quantity is called the INERTIA OF ELECTRICITY? Why is its 
called so?  
8. Define self induction and self inductance. What is its unit? Write its dimensions. 
9. Derive an expression for the self inductance of a long solenoid. 
10. Explain the phenomenon of mutual induction and define mutual inductance. Write 
the unit and dimensions of mutual inductance. 
11. What are the factors affecting mutual inductance of a pair of coils? Define 
coefficient of coupling. 
12. Describe the various methods of producing induced emf. Derive an expression for 
the instantaneous emf induced in a coil rotated in a magnetic field. 
13. What is displacement current? Explain its need. 
Alternative Current- 
1. Describe the principle construction and working of an AC generator. Draw neat 
labeled diagram 
2. Define mean value of AC(over a half cycle) and derive an expression for it. 
3. Define RMS value of AC and derive an expression for it. () 
4. Show that the average value of AC over a complete cycle is zero. 
5. Show that the current and voltage are in phase in an ac circuit containing resistance 
only. 
6. Deduce the phase relationship between current and voltage in an ac circuit 
containing inductor only. 
7. Deduce the phase relationship between current and voltage in an ac circuit 
containing capacitor only. 
8. Draw the phasor diagram showing voltage and current in LCR series circuit and 
derive an expression for the impedance 
9. What do you mean by resonance in Series LCR circuit? Derive an expression for 
the frequency of resonance in LCR circuit. 
10. Distinguish between resistance, reactance and impedance. 
11. Define quality factor (Q factor) of resonance and derive an expression for it. 
12. Describe the mechanism of electromagnetic oscillations in LC circuit and write 
expression for the frequency of oscillations produced. 
13. Derive an expression for the average power in an ac circuit. 
14. Define power factor. Deduce expression for it and explain wattless current? 
15. Describe the principle construction theory and working of a transformer. 
16. Describe the various losses in a transformer and explain how the losses can be 
minimized. 
Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 4 
 
 
Electromagnetic Waves- 
1. Explain the inadequacy of Ampere's circuital law 
2. Describe Hertz experiment to demonstrate the production of electromagnetic 
waves 
3. Write the properties of electromagnetic waves. 
4. Write any five electromagnetic waves in the order of decreasing frequency and 
write any two properties and uses of each 
5. Deduce an expression for velocity of em waves in vacuum 
6. Establish the transverse nature of electromagnetic waves. 
7.  Compare the properties of electromagnetic waves and mechanical waves 
Ray-Optics- 
1. Derive mirror formula for a concave mirror and convex mirror. 
2. Derive an expression for lateral shift and normal shift. On what factors these 
depend. 
3. Define TIR and write the conditions for TIR. Derive a relation between critical 
angle and the refractive index of the medium. Also explain the working of 
isosceles prism and optical fiber. 
4. Derive the following relation for a real image formed by a convex refracting 
surface when the object is placed in rarer medium. Also write the assumptions and 
sign convention used. 
5.     
2 1 2 1
v u R
? ? ? ? ?
??
 
6. Derive the lens maker’s formula. Also write the assumptions and sign convention 
used. 
7. Derive the lens formula for convex lend and concave lens. 
8. Derive the relation for equivalent focal length or power when two thin lenses are 
placed in contact to each other. In which condition the lens combination will act as 
a plane glass sheet. 
9. Derive the following relations for a prism- 
()      
( )     ( 1)
()
sin
2
( )    
sin / 2
m
i i e A
ii A
A
iii
A
?
??
?
?
? ? ?
??
?
?
 
10. Where the symbols have their usual meanings. 
11. Draw a ray diagram to show the image formation in refracting type astronomical 
telescope in the near point adjustment (when image is formed at LDDV i.e. 
D=25cm). Derive an expression for its magnifying power. Why the diameter of 
objective of telescope should be large. 
Page 5


Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 1 
 
 
Electrostatics- 
1. Derive an expression for the electric field at a point on the axial position of an 
electric dipole. 
2. Derive an expression for the electric field at a point on the equatorial position of an 
electric dipole. 
3. Describe the Principle, construction and working of Van de Graff generator. 
4. Derive an expression for the energy stored in a capacitor. Show that whenever two 
conductors share charges by bringing them into electrical contact, there is a loss of 
energy. 
5. Derive an expression for the effective capacitance when capacitors are connected 
in (a) series and (b) parallel 
6. Explain the principle of a capacitor and derive an expression for the capacitance of 
a parallel plate capacitor. 
7.  State Gauss theorem and apply it to find the electric field at a point due to (a) a 
line of charge (b) A plane sheet of charge (c) A Charged spherical conducting shell 
8. State Coulomb's law and express it in vector form. Derive it using Gauss theorem. 
9. Derive an expression for the torque on an electric dipole in a uniform electric field. 
10. Derive an expression for the work done in rotating an electric dipole in a uniform 
electric field 
11. Derive an expression for the energy stored (Potential Energy) in a dipole in a 
uniform electric field. 
12. Derive an expression for the electrostatic potential energy of a system of point 
charges 
13. Derive an expression for the capacitance of a parallel plate capacitor with (a) a 
dielectric slab (b) a metallic plate in between the plates of the capacitor. 
14. Define electric potential at a point. Derive an expression for the electric potential at 
a point due to (a) a point charge (b) a system of point charges (c) a dipole. 
15. Show that the work done in an electric field is independent of path. 
16. What are dielectrics? Distinguish polar and nonpolar dielectrics. Define the term 
Polarization vector. 
Current Electricity- 
1. Define drift velocity and derive an expression for it. 
2. Derive the expression I=nAev
d
 
3. Deduce Ohm's law from elementary ideas and hence write an expression for 
resistance and resistivity. 
4. Derive an expression for conductivity in terms of mobility 
5. Explain the color coding of carbon resistors. 
6. Derive an expression for the current in a circuit with external resistance R when (a) 
n identical cells of emf E and internal resistance r are connected in series (b) m 
identical cells are connected in parallel 
7. State and explain Kirchhoff’s laws. 
Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 2 
 
 
8. State and explain the principle of Wheat Stone's principle. Deduce it using 
Kirchhoff’s laws. 
9. Describe how you will determine the resistance of a given wire using Meter 
Bridge. 
10. Explain the principle of a potentiometer. Describe how will you determine (a) the 
ratio of emfs of two primary cells using potentiometer. (b) The internal resistance 
of a primary cell using potentiometer. 
11. Explain the variation of resistance and resistivity with temperature and hence 
define temperature coefficient of resistance and resistivity. 
Magnetic Effect of Current 
1. State Biot- Savart law and apply it to find the magnetic field due to a circular loop 
carrying current at a point (a) at its centre (b) on the axis 
2. State Ampere's circuital law and apply it to find the magnetic field (a) inside a 
current carrying solenoid (b) inside a current carrying toroid 
3. Apply Ampere's circuital law to determine the magnetic field at a point due to a 
long straight current carrying conductor. 
4. Derive an expression for the force on a current carrying conductor in a uniform 
magnetic field 
5. Derive an expression for the force between long straight conductors carrying 
current and hence define 1 ampere. 
6.  Derive an expression for the torque on a current carrying loop in a uniform 
magnetic field. 
7. Describe the principle construction and working of a Moving coil galvanometer. 
8. Describe the conversion of a moving coil galvanometer into (a) Ammeter (b) 
Voltmeter 
9. What is radial magnetic field? What is its importance in a moving coil 
galvanometer? How is a radial magnetic field realized in moving coil 
galvanometers? 
10. Describe the principle construction and working of a cyclotron. Explain why an 
electron cannot be accelerated using a cyclotron. 
11. Describe the motion of a charged particle in a magnetic field when it enters the 
field (a) perpendicular to the field lines (b) obliquely making and angle T with the 
field lines 
12. Derive an expression for the magnetic dipole moment of a revolving electron and 
hence define Bohr magneton. 
Electromagnetic Induction (EMI)- 
1. State and Explain Faraday's laws of electromagnetic induction.() 
2. State Lenz' Law and show that it is in accordance with the law of conservation of 
energy. 
3. Use Lenz' law to find the direction of induced emf in a coil when (a) a north pole is 
brought towards the coil (b) north pole taken away from the coil (c) A south pole is 
Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 3 
 
 
brought towards the coil and (d) a south pole is taken away from the coil, Draw 
illustrations in each case. 
4. What is motional emf. Deduce an expression for it. State Fleming's right hand rule 
to find the direction of induced emf. 
5. What are eddy currents? Describe the applications of eddy currents. 
6. Explain the working of (a) Electromagnetic Brakes (b) Induction Furnace 
7. Which physical quantity is called the INERTIA OF ELECTRICITY? Why is its 
called so?  
8. Define self induction and self inductance. What is its unit? Write its dimensions. 
9. Derive an expression for the self inductance of a long solenoid. 
10. Explain the phenomenon of mutual induction and define mutual inductance. Write 
the unit and dimensions of mutual inductance. 
11. What are the factors affecting mutual inductance of a pair of coils? Define 
coefficient of coupling. 
12. Describe the various methods of producing induced emf. Derive an expression for 
the instantaneous emf induced in a coil rotated in a magnetic field. 
13. What is displacement current? Explain its need. 
Alternative Current- 
1. Describe the principle construction and working of an AC generator. Draw neat 
labeled diagram 
2. Define mean value of AC(over a half cycle) and derive an expression for it. 
3. Define RMS value of AC and derive an expression for it. () 
4. Show that the average value of AC over a complete cycle is zero. 
5. Show that the current and voltage are in phase in an ac circuit containing resistance 
only. 
6. Deduce the phase relationship between current and voltage in an ac circuit 
containing inductor only. 
7. Deduce the phase relationship between current and voltage in an ac circuit 
containing capacitor only. 
8. Draw the phasor diagram showing voltage and current in LCR series circuit and 
derive an expression for the impedance 
9. What do you mean by resonance in Series LCR circuit? Derive an expression for 
the frequency of resonance in LCR circuit. 
10. Distinguish between resistance, reactance and impedance. 
11. Define quality factor (Q factor) of resonance and derive an expression for it. 
12. Describe the mechanism of electromagnetic oscillations in LC circuit and write 
expression for the frequency of oscillations produced. 
13. Derive an expression for the average power in an ac circuit. 
14. Define power factor. Deduce expression for it and explain wattless current? 
15. Describe the principle construction theory and working of a transformer. 
16. Describe the various losses in a transformer and explain how the losses can be 
minimized. 
Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 4 
 
 
Electromagnetic Waves- 
1. Explain the inadequacy of Ampere's circuital law 
2. Describe Hertz experiment to demonstrate the production of electromagnetic 
waves 
3. Write the properties of electromagnetic waves. 
4. Write any five electromagnetic waves in the order of decreasing frequency and 
write any two properties and uses of each 
5. Deduce an expression for velocity of em waves in vacuum 
6. Establish the transverse nature of electromagnetic waves. 
7.  Compare the properties of electromagnetic waves and mechanical waves 
Ray-Optics- 
1. Derive mirror formula for a concave mirror and convex mirror. 
2. Derive an expression for lateral shift and normal shift. On what factors these 
depend. 
3. Define TIR and write the conditions for TIR. Derive a relation between critical 
angle and the refractive index of the medium. Also explain the working of 
isosceles prism and optical fiber. 
4. Derive the following relation for a real image formed by a convex refracting 
surface when the object is placed in rarer medium. Also write the assumptions and 
sign convention used. 
5.     
2 1 2 1
v u R
? ? ? ? ?
??
 
6. Derive the lens maker’s formula. Also write the assumptions and sign convention 
used. 
7. Derive the lens formula for convex lend and concave lens. 
8. Derive the relation for equivalent focal length or power when two thin lenses are 
placed in contact to each other. In which condition the lens combination will act as 
a plane glass sheet. 
9. Derive the following relations for a prism- 
()      
( )     ( 1)
()
sin
2
( )    
sin / 2
m
i i e A
ii A
A
iii
A
?
??
?
?
? ? ?
??
?
?
 
10. Where the symbols have their usual meanings. 
11. Draw a ray diagram to show the image formation in refracting type astronomical 
telescope in the near point adjustment (when image is formed at LDDV i.e. 
D=25cm). Derive an expression for its magnifying power. Why the diameter of 
objective of telescope should be large. 
Chapter wise Theoretical Important Questions in Physics for Class-XII   
 
 Page 5 
 
 
12. Draw a ray diagram to show the image formation in refracting type astronomical 
telescope in the normal adjustment (when image is formed at infinity). Derive an 
expression for its magnifying power. How does the magnifying power get affected 
on increasing the aperture of the objective lens and why? 
13. Draw a ray diagram to show the image formation a compound microscope. Explain 
briefly the working. Derive an expression for its magnifying power. Why the 
diameter of objective of microscope should be small. 
14. Draw a labeled diagram of a reflecting type telescope. State two advantages of this 
telescope over refracting type telescope. 
15. Define resolving power of compound microscope. How does the resolving power 
of a compound microscope change when-(a) Refractive index of medium between 
the object and objective lens increases (b) Wavelength of the light used is 
increased (c) decreasing the diameter of objective (iv) increasing the focal length 
of its objective. 
16. Define the resolving power of astronomical telescope. Write the expression for it 
and state, on what factors it depends 
Wave-Optics- 
1. Define wave front. State Huygens principle and verify Snell’s law. 
2. State Huygens principle and prove the laws of reflection on the basis of wave 
theory. 
3. What do you mean by interference of light? Explain in brief the Young’s double 
slit experiment. 
4. What are the coherent sources? Write the conditions for the sustained interference 
pattern. Also draw the intensity v/s path difference curve. 
5. Find the conditions for constructive and destructive interference. How does the 
intensity depend on the width of slit? 
6. Find the expression for the fringe width. What is the effect on the fringe width if 
the whole apparatus (YDSE) is completely immersed in a liquid of refractive index 
µ? 
7. What do you mean by diffraction of light and state the condition for the 
diffraction? Obtain the conditions for secondary maxima and minima. Also draw 
the intensity distribution curve. 
8. Prove that the width of central maxima is twice the width of the secondary 
maxima. How does the width of central maxima depend on the width of the slit? 
9. State Brewster’s law and prove that the reflected and refracted rays are mutually 
perpendicular at the angle of polarization. 
10. State law of Malus and draw an intensity V/s angle between the plane of 
transmission of polarizer and analyzer. 
11. What is a Polaroid? How are they constructed? Mention their important 
applications.