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All questions of Resistance, Resistivity, and Ohm’s Law for EmSAT Achieve Exam
The current in a coil of resistance 90 ohms is to be reduced by 90 percent. What value of resistance should be connected in parallel with it?- a)100Ω
- b)10Ω
- c)9Ω
- d)90Ω
Correct answer is option 'B'. Can you explain this answer?
The current in a coil of resistance 90 ohms is to be reduced by 90 percent. What value of resistance should be connected in parallel with it?
a)
100Ω
b)
10Ω
c)
9Ω
d)
90Ω
|
Anjana Sharma answered |
The resistance is connected in parallel. Hence, voltage across the required resistance S and 90Ω is the same, i.e.
0.9 I x S = 0.1 I x 90
S = 90/9= 10Ω
V-I graph of which material shows the straight line- a)Silicon
- b)Silver
- c)Germanium
- d)Gallium
Correct answer is option 'B'. Can you explain this answer?
V-I graph of which material shows the straight line
a)
Silicon
b)
Silver
c)
Germanium
d)
Gallium
|
Riya Banerjee answered |
Materials which obeys the ohm’s law show straight line in the V-I graph. Since silver is the only ohmic material in given options, it shows straight line curve.
Which of the following is an ohmic conductor?- a)LED
- b)Thyristor
- c)diode
- d)Metal conductor
Correct answer is option 'D'. Can you explain this answer?
Which of the following is an ohmic conductor?
a)
LED
b)
Thyristor
c)
diode
d)
Metal conductor
|
Geetika Shah answered |
Ohmic conductors are those which follows ohm's Law
Constantan is an copper nickle alloy which follows ohm's law
An electrolyte is a chemical that produces an electrically conducting solution and hence conducts electrical current.
But Electrolyte can be Ohmic as well as non-ohmic conductor
Transistor is semi-conductor device and does not follow ohm's Law
thermionic valves - is vacuum tube (electronic tube) , uses ion emission.
So option C Constanton s an ohmic conductor.
A current of 2 ampere is passing through a metallic wire of cross-sectional area 2 x 10-6 m2. If the density of the charge carriers in the wire is 5 x 1026 m-3, then the drift velocity of the electrons will be- a)1.15 x 10-6 m/s
- b)1.5 x 10-5 m/s
- c)1.25 x 10-2 m/s
- d)1.05 x 10-3 m/s
Correct answer is option 'C'. Can you explain this answer?
A current of 2 ampere is passing through a metallic wire of cross-sectional area 2 x 10-6 m2. If the density of the charge carriers in the wire is 5 x 1026 m-3, then the drift velocity of the electrons will be
a)
1.15 x 10-6 m/s
b)
1.5 x 10-5 m/s
c)
1.25 x 10-2 m/s
d)
1.05 x 10-3 m/s
|
Preeti Khanna answered |
Drift velocity, v=I/nAe
=2/(2x10-6)x(5x1026)x(1.6x10-19)
=1.25x10-2m/s
=2/(2x10-6)x(5x1026)x(1.6x10-19)
=1.25x10-2m/s
- a)
- b)
- c)
- d)
Correct answer is 'C'. Can you explain this answer?
|
Mira Joshi answered |
F=-eE .
we know that,
F= ma ,
then
a=F/m.
a=-eE/m.
we know that,
F= ma ,
then
a=F/m.
a=-eE/m.
The following fig. shows I-V graph for a given metallic wire at two temperatures T1and T2.Then,
- a)Temperature T2 is less
- b)Temperature T2 is more
- c)T1 is same as T2
- d)None of the above
Correct answer is option 'B'. Can you explain this answer?
The following fig. shows I-V graph for a given metallic wire at two temperatures T1and T2.Then,
a)
Temperature T2 is less
b)
Temperature T2 is more
c)
T1 is same as T2
d)
None of the above
|
Knowledge Hub answered |
The slope of the graph = I / V
In case of T2, I/V is less. Hence, V/I (=R) is more.
Value of resistance increases with increasing temperature.
Hence, T2 >T
Five resistances are connected as shown in fig. The effective resistance between points A and B is
- a)20/30Ω
- b)15Ω
- c)10/3Ω
- d)6Ω
Correct answer is option 'C'. Can you explain this answer?
Five resistances are connected as shown in fig. The effective resistance between points A and B is
a)
20/30Ω
b)
15Ω
c)
10/3Ω
d)
6Ω
|
Lekshmi Basu answered |
The given circuit is a balanced Wheatstone bridge type, hence it can be simplified 
How many electrons are flowing per second through a section of a conductor corresponding to current of 1A?- a)7. 00 × 1018
- b)6.25 × 1018
- c)3.25 × 1016
- d)4.75 × 1017
Correct answer is 'B'. Can you explain this answer?
How many electrons are flowing per second through a section of a conductor corresponding to current of 1A?
a)
7. 00 × 1018
b)
6.25 × 1018
c)
3.25 × 1016
d)
4.75 × 1017
|
Vishal Giri answered |
I = q / t but we know q = n*e# where n = no. of electrons and e = charge on one electron. Let's put:: q=n*e we get I = n*e / t we know from given information that =============>I = 1A,,,,, t =1 s,,,, e = 1.602 * 10^ -19 C. put all these values in above equation we get 1 = n* 1.6 *10^ -19/ 1 hence n = 1 / 1.6*10^ -19 n = 0.625 * 10^ 19 n = 6.25 * 10^ 18IS THE UR ANSWER.
Specific resistance of a conductor increases with- a)Increase in cross-section and decrease in length
- b)Increase in cross-section
- c)Decrease in cross-section
- d)Increase in temperature
Correct answer is option 'D'. Can you explain this answer?
Specific resistance of a conductor increases with
a)
Increase in cross-section and decrease in length
b)
Increase in cross-section
c)
Decrease in cross-section
d)
Increase in temperature
|
|
Anjana Sharma answered |
Therefore resistance increases with the length. When cross sectional area increases the space of the elctrons to travel increases(simply explained). Therefore less amount of obstacles for the current. Therefore when area increases the resistance decreases.
Three resistors of 4Ω, 12Ω , and 6Ω are connected in parallel. No. of 12Ω resistors required to be connected in parallel to reduce the total resistance to half of its original is- a)6
- b)3
- c)12
- d)2
Correct answer is 'A'. Can you explain this answer?
Three resistors of 4Ω, 12Ω , and 6Ω are connected in parallel. No. of 12Ω resistors required to be connected in parallel to reduce the total resistance to half of its original is
a)
6
b)
3
c)
12
d)
2
|
|
Riya Banerjee answered |
Here 4 Ω, 12 Ω, 6 Ω when connected in parallel results in 2Ω. to reduce it to half we have to join 1\R original = 6\12 for reducing it to half we have to join 6 , 12 Ω resistors in parallel (6\12) + (1\ 12 × 6) = 12\12 = 1 ohm . Half of its original value therefore option a is correct.
1 ohm is equal to- a)1 volt per ampere
- b)1 ampere per millivolt
- c)1 milliampere per volt
- d)1 ampere per volt
Correct answer is option 'A'. Can you explain this answer?
1 ohm is equal to
a)
1 volt per ampere
b)
1 ampere per millivolt
c)
1 milliampere per volt
d)
1 ampere per volt
|
|
Anjana Sharma answered |
Reduced to base SI units, one ohm is the equivalent of one kilogram meter squared per second cubed per ampere squared (1 kg times m. s. A^-2 . The ohm is also the equivalent of a volt per ampere (V/A).
If the potential difference V applied on a conductor is doubled, the drift velocity of electrons will become- a)vd
- b)2vd
- c)4vd
- d)
Correct answer is option 'B'. Can you explain this answer?
If the potential difference V applied on a conductor is doubled, the drift velocity of electrons will become
a)
vd
b)
2vd
c)
4vd
d)
|
EduRev JEE answered |
Drift velocity is directly proportional to potential difference.
Drift velocity is defined as the average velocity with which free electrons get drifted towards the positive end of the conductor under the influence of an external electric field.
Drift velocity is given by
vd= eEτ/ m
But, E=V/l
(if l is length of the conductor and V is constant potential difference applied across the ends of the conductor)
∴vd= eVτ/ml
⇒vd∝V
So, when the potential difference is doubled the drift velocity will be doubled.
Note - Current flowing through a conductor is directly proportional to the drift velocity.
Drift velocity is defined as the average velocity with which free electrons get drifted towards the positive end of the conductor under the influence of an external electric field.
Drift velocity is given by
vd= eEτ/ m
But, E=V/l
(if l is length of the conductor and V is constant potential difference applied across the ends of the conductor)
∴vd= eVτ/ml
⇒vd∝V
So, when the potential difference is doubled the drift velocity will be doubled.
Note - Current flowing through a conductor is directly proportional to the drift velocity.
Can you explain the answer of this question below:What is current I in the circuit as shown in figure?
- A:
1 A
- B:
2.0 A
- C:
1.2 A
- D:
0.5 A
The answer is b.
What is current I in the circuit as shown in figure?
1 A
2.0 A
1.2 A
0.5 A
|
Surya answered |
Yes option B is correct... first u straight the three resistance then it change in series... so u add three u get 6 ohms... after, that 6 ohm is parallel to 3ohm so;3/2.. so as per ohms law;V=IR (since:V=3; R=3/2; I=?) 3=3/2×I I=2ampere... that's it...hope u clear...!!👍😊
On heating a conductor its resistance- a)depends on type of metal
- b)remains constant
- c)increases
- d)decreases
Correct answer is option 'C'. Can you explain this answer?
On heating a conductor its resistance
a)
depends on type of metal
b)
remains constant
c)
increases
d)
decreases
|
|
Rahul Bansal answered |
The resistance increases as the temperature of a metallic conductor increase, so the resistance is directly proportional to the temperature. When we increase the temperature the amplitude of vibration of atoms increases as a result of which the number of collision among the electrons and atom increases, and hence resistances increases.
A carbon resistor is marked in green, red, and orange bands. The approximate resistance of the resistor is
- a)52 x 103 Ω
- b)25000 Ω
- c)5 x 102 Ω
- d)5 x 104 Ω
Correct answer is option 'A'. Can you explain this answer?
A carbon resistor is marked in green, red, and orange bands. The approximate resistance of the resistor is
a)
52 x 103 Ω
b)
25000 Ω
c)
5 x 102 Ω
d)
5 x 104 Ω
|
|
Anjana Sharma answered |
To determine the resistance of a carbon resistor based on the color bands, we need to refer to the standard resistor color code. The colors represent digits and multipliers as follows:
- Green: 5
- Red: 2
- Orange: Multiplier of 10^3 (1,000)
Given the color bands: Green, Red, Orange
The resistance value is calculated as follows:
- First digit: Green = 5
- Second digit: Red = 2
- Multiplier: Orange = 10^3 (1,000)
So the resistance is:
Resistance=(52)×10^3 ohms=52,000 ohms=52 kilo-ohms
Answer: The approximate resistance of the resistor is 52 kΩ.
Manganin and constantan have a low temperature coefficient of resistivity which means that- a)their resistance values change very little with temperature
- b)their resistance values only change at low temperatures
- c)their resistance values change greatly with temperature
- d)their resistance values do not change with temperature
Correct answer is option 'A'. Can you explain this answer?
Manganin and constantan have a low temperature coefficient of resistivity which means that
a)
their resistance values change very little with temperature
b)
their resistance values only change at low temperatures
c)
their resistance values change greatly with temperature
d)
their resistance values do not change with temperature
|
|
Rajat Kapoor answered |
The semiconductors and insulating material are having negative temperature coefficient of resistance. Therefore, the resistance of semiconductors and insulators decrease with rise in temperature. Alloys, such as manganin, constantan etc. are having very low and positive temperature coefficient of resistance.
Two special characteristics of the element of an electric heater:- a)low resistivity and high melting point
- b)low resistivity and low melting point
- c)high resistivity and low melting point
- d)high resistivity and high melting point
Correct answer is option 'D'. Can you explain this answer?
Two special characteristics of the element of an electric heater:
a)
low resistivity and high melting point
b)
low resistivity and low melting point
c)
high resistivity and low melting point
d)
high resistivity and high melting point
|
Samiksha Narwade answered |
Electric heater is device to heat water.... So when it have high melting pt. it we sustain heat nd won't melt....nd resistance means to oppose heat... So it should have high resistivity to heat water without getting damage....HOPE THIS WILL HELP YOU....!
The dimension of the temperature coefficient of resistivity is- a)(temperature.ohm)-1
- b)same as temperature.ohm
- c)same as (temperature)-1
- d)same as (temperature)2
Correct answer is option 'C'. Can you explain this answer?
The dimension of the temperature coefficient of resistivity is
a)
(temperature.ohm)-1
b)
same as temperature.ohm
c)
same as (temperature)-1
d)
same as (temperature)2
|
|
Ameya Pillai answered |
Temperature Coefficient of Resistivity
The temperature coefficient of resistivity is defined as the change in the electrical resistance of a material per unit change in temperature. It is denoted by the symbol α and has units of inverse temperature (K^-1) or reciprocal temperature (1/T).
Effect of Temperature on Electrical Resistance
When the temperature of a conductor increases, its electrical resistance also increases. This is due to the fact that as the temperature increases, the atoms in the conductor vibrate more vigorously, which results in more collisions between the electrons and the atoms. This increase in collisions leads to an increase in the resistance of the conductor.
Formula for Temperature Coefficient of Resistivity
The temperature coefficient of resistivity is given by the formula:
α = (1/ρ) x (dρ/dT)
where ρ is the resistivity of the material and dρ/dT is the rate of change of the resistivity with temperature.
Dimension of Temperature Coefficient of Resistivity
The dimension of the temperature coefficient of resistivity is the same as that of reciprocal temperature or (temperature)^-1. This can be seen from the formula for the temperature coefficient of resistivity:
α = (1/ρ) x (dρ/dT)
where ρ has units of ohm-meters (Ω.m) and dρ/dT has units of ohm-meters per Kelvin (Ω.m/K). Thus, the units of α are K^-1 or 1/T.
Conclusion
In conclusion, the temperature coefficient of resistivity is a measure of how the electrical resistance of a material changes with temperature. It has units of inverse temperature or reciprocal temperature, and its dimension is the same as that of (temperature)^-1.
The temperature coefficient of resistivity is defined as the change in the electrical resistance of a material per unit change in temperature. It is denoted by the symbol α and has units of inverse temperature (K^-1) or reciprocal temperature (1/T).
Effect of Temperature on Electrical Resistance
When the temperature of a conductor increases, its electrical resistance also increases. This is due to the fact that as the temperature increases, the atoms in the conductor vibrate more vigorously, which results in more collisions between the electrons and the atoms. This increase in collisions leads to an increase in the resistance of the conductor.
Formula for Temperature Coefficient of Resistivity
The temperature coefficient of resistivity is given by the formula:
α = (1/ρ) x (dρ/dT)
where ρ is the resistivity of the material and dρ/dT is the rate of change of the resistivity with temperature.
Dimension of Temperature Coefficient of Resistivity
The dimension of the temperature coefficient of resistivity is the same as that of reciprocal temperature or (temperature)^-1. This can be seen from the formula for the temperature coefficient of resistivity:
α = (1/ρ) x (dρ/dT)
where ρ has units of ohm-meters (Ω.m) and dρ/dT has units of ohm-meters per Kelvin (Ω.m/K). Thus, the units of α are K^-1 or 1/T.
Conclusion
In conclusion, the temperature coefficient of resistivity is a measure of how the electrical resistance of a material changes with temperature. It has units of inverse temperature or reciprocal temperature, and its dimension is the same as that of (temperature)^-1.
The following fig. shows I-V graph for a given metallic wire at two temperatures T1and T2.Then,
- a)Temperature T2 is less
- b)Temperature T2 is more
- c)T1 is same as T2
- d)None of the above
Correct answer is option 'C'. Can you explain this answer?
The following fig. shows I-V graph for a given metallic wire at two temperatures T1and T2.Then,
a)
Temperature T2 is less
b)
Temperature T2 is more
c)
T1 is same as T2
d)
None of the above
|
|
Rahul Bansal answered |
The slope of the given graph gives us the inverse of resistance. Resistance of a material increases with increasing temperature because the collision between the molecules increases.
In the graph given, T2 has a smaller slope and hence corresponds to higher resistance. Therefore, T2 > T1.
What is current I in the circuit as shown in figure?
- a)1 A
- b)2.0 A
- c)1.2 A
- d)0.5 A
Correct answer is option 'B'. Can you explain this answer?
What is current I in the circuit as shown in figure?
a)
1 A
b)
2.0 A
c)
1.2 A
d)
0.5 A
|
|
Preeti Iyer answered |
Three 2Ω resistors are in series. Their total resistance =6Ω. Now it is in parallel with 2Ω resistor, so total resistance,
1/R=1/2+1/6=3+1/6=4/6=2/3
R=3/2
∴I=RV=3/(3/2)=3×2/3=2A
1/R=1/2+1/6=3+1/6=4/6=2/3
R=3/2
∴I=RV=3/(3/2)=3×2/3=2A
Resistors can be wire bound or carbon resistors. Wire bound resistors are generally made of- a)Aluminium
- b)Carbon
- c)Copper
- d)Manganin
Correct answer is option 'D'. Can you explain this answer?
Resistors can be wire bound or carbon resistors. Wire bound resistors are generally made of
a)
Aluminium
b)
Carbon
c)
Copper
d)
Manganin
|
|
Anjana Sharma answered |
The wire material has a high resistivity, and is usually made of an alloy such as Nickel-chromium (Nichrome) or a copper-nickel-manganese alloy called Manganin. Common core materials include ceramic, plastic and glass. Wire wound resistors are the oldest type of resistors that are still manufactured today.
A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along the length of the conductor is/are- a)Current and drift speed
- b)Current, electric field and drift velocity
- c)Speed only
- d)Current only.
Correct answer is option 'D'. Can you explain this answer?
A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along the length of the conductor is/are
a)
Current and drift speed
b)
Current, electric field and drift velocity
c)
Speed only
d)
Current only.
|
|
Rahul Bansal answered |
Steady current implies current is uniform across the cross-section.
Since current is constant, current per unit area and hence drift velocity are not constant.
J = nevd = σE
The above relation shows that nothing apart from the current is constant.
The type of materials whose resistivity is affected on adding the impurity is known as- a)Semiconductor
- b)Insulator
- c)Iron alloys
- d)Conductor
Correct answer is option 'A'. Can you explain this answer?
The type of materials whose resistivity is affected on adding the impurity is known as
a)
Semiconductor
b)
Insulator
c)
Iron alloys
d)
Conductor
|
Vijay Bansal answered |
Semiconductor - A material that is neither a good conductor of electricity nor a good insulator, but has properties of electrical conductivity somewhere between the two. Silicon and germanium are good semiconductor materials.
Three resistors of 4Ω, 12Ω , and 6Ω are connected in parallel. No. of 12Ω resistors required to be connected in parallel to reduce the total resistance to half of its original is- a)6
- b)3
- c)12
- d)2
Correct answer is 'A'. Can you explain this answer?
Three resistors of 4Ω, 12Ω , and 6Ω are connected in parallel. No. of 12Ω resistors required to be connected in parallel to reduce the total resistance to half of its original is
a)
6
b)
3
c)
12
d)
2
|
Sanchita Iyer answered |
Understanding Parallel Resistance
In a parallel circuit, the total resistance (R_total) is calculated using the formula:
1/R_total = 1/R1 + 1/R2 + 1/R3 + ...
For the given resistors:
- R1 = 4 ohms
- R2 = 12 ohms
- R3 = 6 ohms
Calculating the Original Total Resistance
Let's find the total resistance with the existing resistors.
- 1/R_total = 1/4 + 1/12 + 1/6
Finding a common denominator (which is 12):
- 1/R_total = 3/12 + 1/12 + 2/12 = 6/12
Thus,
- R_total = 2 ohms.
Target Resistance
We want to reduce the total resistance to half of its original value:
- Target Resistance = 2 ohms / 2 = 1 ohm.
Adding 12 Ohm Resistors
Let 'n' be the number of additional 12 ohm resistors needed in parallel to reach 1 ohm.
The new total resistance formula becomes:
1/R_new = 1/R_total + n/R2
Where R2 is 12 ohms:
1/R_new = 1/2 + n/12.
Setting R_new to 1 ohm gives:
1 = 1/2 + n/12.
Rearranging the equation:
1 - 1/2 = n/12
1/2 = n/12
Thus, n = 6.
Conclusion
To achieve a total resistance of 1 ohm, you need to connect 6 additional 12 ohm resistors in parallel. Hence, the correct answer is:
A) 6
In a parallel circuit, the total resistance (R_total) is calculated using the formula:
1/R_total = 1/R1 + 1/R2 + 1/R3 + ...
For the given resistors:
- R1 = 4 ohms
- R2 = 12 ohms
- R3 = 6 ohms
Calculating the Original Total Resistance
Let's find the total resistance with the existing resistors.
- 1/R_total = 1/4 + 1/12 + 1/6
Finding a common denominator (which is 12):
- 1/R_total = 3/12 + 1/12 + 2/12 = 6/12
Thus,
- R_total = 2 ohms.
Target Resistance
We want to reduce the total resistance to half of its original value:
- Target Resistance = 2 ohms / 2 = 1 ohm.
Adding 12 Ohm Resistors
Let 'n' be the number of additional 12 ohm resistors needed in parallel to reach 1 ohm.
The new total resistance formula becomes:
1/R_new = 1/R_total + n/R2
Where R2 is 12 ohms:
1/R_new = 1/2 + n/12.
Setting R_new to 1 ohm gives:
1 = 1/2 + n/12.
Rearranging the equation:
1 - 1/2 = n/12
1/2 = n/12
Thus, n = 6.
Conclusion
To achieve a total resistance of 1 ohm, you need to connect 6 additional 12 ohm resistors in parallel. Hence, the correct answer is:
A) 6
The average time that elapses between two successive collisions of an electron is called- a)Drift velocity
- b)Free time
- c)Relaxation time
- d)Collision time
Correct answer is option 'C'. Can you explain this answer?
The average time that elapses between two successive collisions of an electron is called
a)
Drift velocity
b)
Free time
c)
Relaxation time
d)
Collision time
|
|
Rohan Singh answered |
Relaxation time is the time interval between two successive collisions of electrons in a conductor, when current flows.
I = nave --> n->no. of free electrons a->area of conductor v->drift velocity e->charge of electron
but v=(eE/m)T--> E-> field m->mass of electron T->Relaxation time
From this, you can find expression of relaxation time.Field is V/length and V=IR.From this you can modify the expression in terms of resistivity.
Mobility of charge carriers in a conductor is given by- a)(charge of an electron).drift velocity/ electric field
- b)drift velocity/ electric field
- c)mass of an electron.(drift velocity/ electric field)
- d)(drift velocity)(electric field)
Correct answer is option 'B'. Can you explain this answer?
Mobility of charge carriers in a conductor is given by
a)
(charge of an electron).drift velocity/ electric field
b)
drift velocity/ electric field
c)
mass of an electron.(drift velocity/ electric field)
d)
(drift velocity)(electric field)
|
|
Rohit Shah answered |
Drift velocity of charge carriers in a conductor depend upon two factors, one is the intensity of applied electric field across the conductor and other is one property of the conductor called Mobility of Charge Carrier. In other words, for applied same electric field, on different metallic conductors there will be different drift velocities of electrons. These drift velocities of electrons depend upon a typical property of conductor called mobility of charge carrier.
For semiconductors, the major factor affecting the value of resistivity when temperature changes is- a)n: the number of free electrons per unit volume
- b)e: the charge of an electron
- c)m: the mass of an electron
- d)τ:average time between collisions
Correct answer is option 'A'. Can you explain this answer?
For semiconductors, the major factor affecting the value of resistivity when temperature changes is
a)
n: the number of free electrons per unit volume
b)
e: the charge of an electron
c)
m: the mass of an electron
d)
τ:average time between collisions
|
Divey Sethi answered |
n increases with temperature and this increase more than compensates any decrease in relaxation time. Hence, for semiconductors resistivity decreases with the increase in temperature.
Conversion of temperature into electric voltage is done with- a)thermometer
- b)resistor
- c)thermistor
- d)rheostat
Correct answer is option 'C'. Can you explain this answer?
Conversion of temperature into electric voltage is done with
a)
thermometer
b)
resistor
c)
thermistor
d)
rheostat
|
|
Harsh Desai answered |
To convert temperature to voltage we can do a precise measurement of the temperature in a room. A NTC resistor or a thermistor
It is used as a sensor that has a strong temperature dependence.
It is used as a sensor that has a strong temperature dependence.
Can you explain the answer of this question below:The following fig. shows I-V graph for a given metallic wire at two temperatures T1and T2.Then,
- A:
Temperature T2 is less
- B:
Temperature T2 is more
- C:
T1 is same as T2
- D:
None of the above
The answer is c.
The following fig. shows I-V graph for a given metallic wire at two temperatures T1and T2.Then,
Temperature T2 is less
Temperature T2 is more
T1 is same as T2
None of the above
|
Juhi Deshpande answered |
Temperature T₁ is higher than the Temperature T₂, this is because If the temperature will increase then by the concept of the the Heating effect of the current, there will be rise in current. Thus, the graph will be having the more slope.
For the Temperature T₂, line is having a small slope than the temperature T₁ because of the high temp., heating is produced as a result current has been increased.
Note ⇒ Ohm's law is only valid in case, the temperature remains constant, but in this expression temperature is not constant therefore, ohm's law will be not valid. But it can me make valid on different temperatures at a time.
Resistance of a conductor depends on- a)length
- b)length, area of cross-section, nature of material, temperature of conductor
- c)length and area of cross-section
- d)length, area of cross-section, nature of material
Correct answer is option 'B'. Can you explain this answer?
Resistance of a conductor depends on
a)
length
b)
length, area of cross-section, nature of material, temperature of conductor
c)
length and area of cross-section
d)
length, area of cross-section, nature of material
|
|
Ashwini Shah answered |
The resistance of a conductor depends on thickness (cross sectional area of the wire), length and temperature.
Resistivity is defined as the measure of the resisting power of a specified material to the flow of an electric current.
R=ρ(I/A)
where R = Resistance of the conductor
ρ = Resistivity of the conductor
l = length of the conductor
A = Area of cross section
i.e., ρ=R (A/l)
Resistivity is defined as the measure of the resisting power of a specified material to the flow of an electric current.
R=ρ(I/A)
where R = Resistance of the conductor
ρ = Resistivity of the conductor
l = length of the conductor
A = Area of cross section
i.e., ρ=R (A/l)
The standard resistance coil are made of “manganin” because- a)Temperature coefficient of resistance remain constant
- b)Temperature coefficient of resistance is very low
- c)Temperature coefficient of resistance is very high
- d)Temperature coefficient of resistance is moderate
Correct answer is option 'B'. Can you explain this answer?
The standard resistance coil are made of “manganin” because
a)
Temperature coefficient of resistance remain constant
b)
Temperature coefficient of resistance is very low
c)
Temperature coefficient of resistance is very high
d)
Temperature coefficient of resistance is moderate
|
Stepway Academy answered |
Answer :- b
Temperature coefficient of resistance is very low
For manganin, the temp coefficient of resistance is very low, and its resistivity is quite large. Due to which the resistance of the manganin wire remains almost unchanged with change in temperature. It is due to this fact; the wire of the manganin is used for making standard resistance coil.
When a conductor is placed in an electric field, the force experienced by its electrons will be- a)
- b)
- c)
in direction
- d)
in opposite direction of
Correct answer is option 'D'. Can you explain this answer?
When a conductor is placed in an electric field, the force experienced by its electrons will be
a)
b)
c)
in directiond)
in opposite direction of
|
Sahana Savalagi answered |
Answer is (d) because the direction that positive test charges are pushed. Thus, these negatively charged electrons move in the direction opposite the electric field.
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