physics : class12 Uniform Potential Gradient : Potentiometer : Current Electricity MCQ Questions and Answers
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Uniform Potential Gradient
MCQ questions and answers.
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MCQ Questions
1. What is meant by the potential gradient of a potentiometer wire?
A.
Potential difference per unit length of the wire
B.
Current flowing per unit length of the wire
C.
Resistance per unit length of the wire
D.
Charge stored per unit length of the wire
Correct Answer:
Potential difference per unit length of the wire
Explanation:
The potential gradient is the potential drop across each unit length of the potentiometer wire. It is given by k = V/L.
2. For a potentiometer wire of length L connected across a potential difference V, the potential gradient is
A.
V + L
B.
V/L
C.
L/V
D.
VL
Correct Answer:
V/L
Explanation:
For a uniform potentiometer wire, the potential gradient k is the total potential difference divided by the wire length: k = V/L.
3. A uniform potentiometer wire has a potential gradient of 0.02 V m⁻¹. What potential difference exists across 3 m of the wire?
A.
0.006 V
B.
0.02 V
C.
0.06 V
D.
0.60 V
Correct Answer:
0.06 V
Explanation:
The potential difference is V = k l = 0.02 × 3 = 0.06 V.
4. In a potentiometer having a uniform potential gradient, the potential drop across a wire is directly proportional to its
A.
Cross-sectional area
B.
Length
C.
Temperature only
D.
Mass
Correct Answer:
Length
Explanation:
With a uniform potential gradient, equal lengths have equal potential drops, so the potential difference is directly proportional to the length.
5. If the potential difference across a uniform potentiometer wire is doubled while its length remains unchanged, its potential gradient becomes
A.
Half
B.
Unchanged
C.
Double
D.
Zero
Correct Answer:
Double
Explanation:
Since k = V/L and L is constant, doubling V doubles the potential gradient.
6. Which condition is necessary for a potentiometer wire to have a uniform potential gradient?
A.
The wire should have uniform resistance per unit length
B.
The wire should have different lengths throughout
C.
The current should be zero everywhere
D.
The potential difference should change randomly
Correct Answer:
The wire should have uniform resistance per unit length
Explanation:
A uniform wire has the same resistance per unit length, producing an equal potential drop per unit length when the current is steady.
7. The SI unit of potential gradient along a potentiometer wire is
A.
Volt
B.
Ohm
C.
Volt per metre
D.
Ampere per metre
Correct Answer:
Volt per metre
Explanation:
Potential gradient is potential difference divided by length, so its SI unit is volt per metre (V m⁻¹).
8. A 4 m uniform potentiometer wire has a potential difference of 2 V across it. What is the potential gradient?
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. On a uniform potentiometer wire, equal lengths have
A.
Equal potential drops
B.
Unequal potential drops
C.
Zero resistance
D.
Different currents necessarily
Correct Answer:
Equal potential drops
Explanation:
A uniform potential gradient means the potential drop per unit length is constant, so equal lengths have equal potential drops.
10. A uniform potentiometer wire has a potential gradient of 0.1 V m⁻¹. What length is required for a potential drop of 0.5 V?
A.
0.05 m
B.
0.5 m
C.
5 m
D.
50 m
Correct Answer:
5 m
Explanation:
Using l = V/k, the required length is 0.5/0.1 = 5 m.