In photoelectric phenomenon, the number of photo electrons emitted depends on
Photoelectric current depends on the intensity of incident light,
the number of photoelectrons emitted per second is directly proportional to the intensity of incident radiation.
A parallel plate condenser with oil between the plates (dielectric constant of oil K = 2) has a capacitance C. If the oil is removed, then capacitance of the capacitors becomes
On removing the oil, the capacitance of the capacitor will become.
C ′ = C/K = C/2
A particle of mass 0. 6 gm and having charge of 25 nC is moving horizontally with a uniform velocity 1.2 x 104 ms-1 in a uniform magnetic field, then the value of the magnetic induction is (g = 10 m s-2 )
For electroplating a spoon, it is placed in the voltameter at
Consider telecommunication through optical fibres. Which of the following statements is not correct
The average power dissipated in a pure inductor of inductance L when an A.C. current is passing through it is
If an electron revolves in the path of a circle of radius of 0.5x 10-10 m at a frequency of 5 x 1015 cycles ∕ sec , the electric current in the circle is (charge of electron = 1.6 x 10-19 C )
The length of given cylindrical wire is increased by 100%. Due to the consequent decrease in diameter the change in the resistance of the wire will be
A wire of radius r has resistance R. If it is stretched to a radius of 3r/4, its resistance becomes
Let L1 be the length and A1 the area of crosssection of the original wire and L2, A2 be their values of the stretched wire
Since volume of the wire remains unchanged, we have
At what temperature, the resistance of a copper wire will become three times its value at 0oC ? (Temperature coefficient of resistance for copper = 4 x 10-3per oC)
If particles are moving with same velocity, then maximum de-Broglie's wavelength will be for
The core of a transformer is laminated so that
A solenoid of length 20 cm area of cross-section 4 cm2 and having 4000 turns is placed inside another solenoid of 2000 turns having a cross-section area 8 cm2 and length 10 cm. The mutual inductance of the system is
Which of the following waves have maximum wavelength?
Two coils are placed close to eachother. The mutual inductance of the pair of coils depends upon
Eight dipoles of charges of magnitude e are placed inside a cube. The total electric flux coming out of the cube will be
Two charges -10 C and + 10 C are placed 10cm apart. Potential at the centre of the line joining two charges is
Two equal charges, q each are placed at a distance of 2a, and a third charge -2q is placed at the mid point. The potential energy of the system is
If an uncharged capacitor is charged by connecting it to a battery, then the amount of energy lost as heat is
Two equal charges q each are placed at a distance of 2a. If a third charge-2q is placed at the mid-point, then potential energy of the system is
In β + decay process, the following changes take place inside the nucleus
A current carrying loop is free to return in a uniform magnetic field. The loop will then come into equilibrium when its plane is inclined at
Which of the following is more effective in inducing nuclear fission
What is the Q-value of the reaction
p + 7 Li → 4 He + 4 He
The atomic masses of 1 H , 4 H e and 7 L i are 1.007825 u, 4.002603 u and 7.016004 u respectively
The photoelectric work function for a metal surface is 4.125 eV. The cut off wavelength for this surface is
Work function W0 = hc/λ
The refractive index of a certain glass is 1.5, for a light of wavelength 6000 Å . When light (c = 3 x 108 m s-1)passed through this glass, its wavelength is
What is the current through an ideal PN-junction diode shown in figure below?
The minimum potential difference between the base and emitter required to switch a silicon transistor 'ON' is approximately
Application of a forward bias to a p-n junction
The intrinsic semiconductor becomes an insulator at
The potential barrier, in the depletion of layer, is due to
The impurity atom that should be added to the germanium to make it an n-type semiconductor, is
Doppler's effects in sound and light are
When a source of light is receding away from an observer, then the spectral lines will get displaced towards
Which of the following property of light waves is not observed in sound waves?
In young's double slit experiment, three light, blue, yellow and red are used successively. For which colour, will the fringe width be maximum?