physics : class12 Standardization of Potentiometer : Potentiometer : Current Electricity MCQ Questions and Answers
Practice important
Standardization of Potentiometer
MCQ questions and answers.
Page 2
of
2
|
19
MCQ Questions
1. During standardization of a potentiometer, what quantity is determined?
A.
Resistance of the galvanometer
B.
Potential gradient of the wire
C.
Current capacity of the standard cell
D.
Internal resistance of the rheostat
Correct Answer:
Potential gradient of the wire
Explanation:
Standardization determines the potential drop per unit length, called the potential gradient, of the potentiometer wire.
2. If a standard cell of emf E balances at length l of the potentiometer wire, the potential gradient k is given by
A.
k = El
B.
k = E/l
C.
k = l/E
D.
k = E + l
Correct Answer:
k = E/l
Explanation:
At balance, the emf of the standard cell equals the potential drop across length l. Therefore, the potential gradient is k = E/l.
3. A standard cell of emf 1.02 V balances at 51 cm on a potentiometer wire. What is the potential gradient?
A.
0.02 V/cm
B.
0.05 V/cm
C.
0.20 V/cm
D.
51 V/cm
Correct Answer:
0.02 V/cm
Explanation:
The potential gradient is k = E/l = 1.02/51 = 0.02 V/cm.
4. In the standardization of a potentiometer, the jockey is moved along the wire to find the point where
A.
The galvanometer shows zero deflection
B.
The wire becomes hot
C.
The rheostat gives maximum resistance
D.
The standard cell gives maximum current
Correct Answer:
The galvanometer shows zero deflection
Explanation:
The balance point is located when the galvanometer shows zero deflection, indicating that the potential difference across the selected wire length equals the emf of the standard cell.
5. Which component is used to adjust the current in the primary circuit during potentiometer standardization?
A.
Galvanometer
B.
Rheostat
C.
Standard cell
D.
Jockey
Correct Answer:
Rheostat
Explanation:
The rheostat controls the current in the primary circuit and hence adjusts the potential gradient along the potentiometer wire.
6. For accurate standardization, the positive terminal of the standard cell should be connected to the
A.
Positive end of the potentiometer wire
B.
Negative end of the potentiometer wire
C.
Galvanometer casing
D.
Rheostat slider only
Correct Answer:
Positive end of the potentiometer wire
Explanation:
The standard cell must be connected with correct polarity so that its emf opposes the potential drop along the potentiometer wire and a balance point can be obtained.
7. If the balance length for a standard cell increases while its emf remains unchanged, the potential gradient has
A.
Increased
B.
Decreased
C.
Remained infinite
D.
Become zero immediately
Correct Answer:
Decreased
Explanation:
Since k = E/l, for constant emf E, an increase in balance length l means that the potential gradient k has decreased.
8. A standard cell of emf 1.5 V balances at 75 cm. What potential difference exists across each centimetre of the wire?
A.
0.02 V
B.
0.05 V
C.
0.50 V
D.
1.50 V
Correct Answer:
0.02 V
Explanation:
The potential gradient is k = E/l = 1.5/75 = 0.02 V/cm, which is the potential difference per centimetre.
9. The potential gradient obtained during standardization is used to determine the emf of an unknown cell by measuring its
A.
Mass
B.
Balance length
C.
Temperature only
D.
Wire thickness only
Correct Answer:
Balance length
Explanation:
Once the potential gradient k is known, the emf of a cell is found from E = kl using the balance length l.