physics : class12 Potentiometer Sensitivity : Potentiometer : Current Electricity MCQ Questions and Answers
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Potentiometer Sensitivity
MCQ questions and answers.
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MCQ Questions
1. The sensitivity of a potentiometer increases when its potential gradient is
A.
increased
B.
decreased
C.
kept unchanged
D.
made equal to the terminal voltage
Correct Answer:
decreased
Explanation:
Potentiometer sensitivity is inversely related to the potential gradient. A smaller potential gradient allows smaller potential differences to be measured accurately.
2. For a potentiometer wire of length L and potential difference V across it, the potential gradient is
A.
VL
B.
V/L
C.
L/V
D.
V + L
Correct Answer:
V/L
Explanation:
The potential gradient is the potential drop per unit length, so it is given by k = V/L.
3. A potentiometer becomes more sensitive if the length of its wire is increased while the potential difference across it remains constant because the potential gradient
A.
increases
B.
decreases
C.
becomes zero
D.
remains infinite
Correct Answer:
decreases
Explanation:
Since k = V/L, increasing L at constant V decreases the potential gradient and increases the sensitivity.
4. Which arrangement provides greater potentiometer sensitivity for the same potential difference across the wire?
A.
A shorter potentiometer wire
B.
A longer potentiometer wire
C.
A wire with zero length
D.
A wire with a broken circuit
Correct Answer:
A longer potentiometer wire
Explanation:
For the same applied potential difference, a longer wire has a smaller potential gradient and therefore greater sensitivity.
5. If the potential gradient of a potentiometer wire is 0.01 V m⁻¹, the potential difference corresponding to a balancing length of 2 m is
A.
0.005 V
B.
0.02 V
C.
0.2 V
D.
2.01 V
Correct Answer:
0.02 V
Explanation:
The balancing potential difference is V = kL = 0.01 × 2 = 0.02 V.
6. A potentiometer is more sensitive when it can measure
Explanation:
Greater sensitivity means that the potentiometer can detect and measure smaller potential differences with greater accuracy.
7. If the current through a uniform potentiometer wire is reduced, its potential gradient generally
A.
increases
B.
decreases
C.
becomes equal to the current
D.
does not depend on the current
Correct Answer:
decreases
Explanation:
The potential gradient is proportional to the current through a uniform potentiometer wire. Reducing the current reduces the potential gradient and increases sensitivity.
8. A potentiometer wire has a potential difference of 2 V across a length of 4 m. Its potential gradient is
A.
0.25 V m⁻¹
B.
0.5 V m⁻¹
C.
2 V m⁻¹
D.
8 V m⁻¹
Correct Answer:
0.5 V m⁻¹
Explanation:
Using k = V/L, the potential gradient is 2/4 = 0.5 V m⁻¹.
9. For a fixed potential difference across a potentiometer wire, sensitivity is directly proportional to the
A.
length of the wire
B.
potential gradient
C.
current density only
D.
voltage per unit length
Correct Answer:
length of the wire
Explanation:
With fixed potential difference, increasing the wire length decreases the potential gradient, making the potentiometer more sensitive.
10. Two potentiometers have the same wire length. The one with a smaller potential difference applied across its wire is
A.
less sensitive
B.
more sensitive
C.
equally sensitive only if its wire is shorter
D.
unable to measure potential difference
Correct Answer:
more sensitive
Explanation:
For the same wire length, a smaller applied potential difference produces a smaller potential gradient, resulting in greater sensitivity.
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