physics : class12 Jockey Function : Potentiometer : Current Electricity MCQ Questions and Answers
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Jockey Function
MCQ questions and answers.
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MCQ Questions
1. What is the main function of the jockey in a potentiometer?
A.
To provide a sliding electrical contact with the potentiometer wire
B.
To supply current to the battery
C.
To measure the resistance of the wire directly
D.
To increase the length of the potentiometer wire
Correct Answer:
To provide a sliding electrical contact with the potentiometer wire
Explanation:
The jockey is a movable contact that touches different points of the potentiometer wire to locate the required balance point.
2. How is the jockey used to find the null point in a potentiometer?
A.
It is moved along the wire until the galvanometer shows zero deflection
B.
It is fixed at the midpoint of the wire
C.
It is moved until the battery becomes fully discharged
D.
It is pressed continuously at the end of the wire
Correct Answer:
It is moved along the wire until the galvanometer shows zero deflection
Explanation:
The jockey is moved over the wire, and the position where the galvanometer shows no deflection is the null or balance point.
3. Why should the jockey of a potentiometer be touched lightly to the wire?
A.
To avoid damaging the wire and changing its resistance
B.
To increase the current through the wire
C.
To make the wire longer
D.
To prevent the battery from producing voltage
Correct Answer:
To avoid damaging the wire and changing its resistance
Explanation:
Light contact prevents damage to the potentiometer wire and avoids disturbing its uniform resistance.
4. What happens when the jockey is moved to different positions on a potentiometer wire?
A.
The length of wire between the end and contact point changes
B.
The total length of the wire changes
C.
The resistance of the battery changes
D.
The galvanometer is disconnected permanently
Correct Answer:
The length of wire between the end and contact point changes
Explanation:
Moving the jockey changes the length of the wire included between the selected end and the contact point, thereby changing the potential drop.
5. The jockey in a potentiometer is connected electrically to which instrument in the secondary circuit?
A.
Galvanometer
B.
Ammeter
C.
Voltmeter only
D.
Rheostat only
Correct Answer:
Galvanometer
Explanation:
The jockey is connected to the galvanometer in the secondary circuit so that zero deflection can be detected at the balance point.
6. What should be done with the jockey while searching for the balance point?
A.
It should be moved gradually along the potentiometer wire
B.
It should remain permanently at one end
C.
It should be removed from the circuit
D.
It should be connected directly across the battery terminals
Correct Answer:
It should be moved gradually along the potentiometer wire
Explanation:
Gradually moving the jockey helps locate the exact position at which the galvanometer shows zero deflection.
7. At the balance point, what is the function of the jockey contact?
A.
It selects the point whose potential matches the potential being compared
B.
It increases the emf of the test cell
C.
It short-circuits the entire potentiometer wire
D.
It stops current in the primary circuit
Correct Answer:
It selects the point whose potential matches the potential being compared
Explanation:
At balance, the jockey touches the point where the potential difference along the wire equals the emf being measured, resulting in zero galvanometer current.
8. Which motion of the jockey is used during a potentiometer experiment?
A.
Sliding motion along the potentiometer wire
B.
Rotational motion around the battery
C.
Vertical motion through the galvanometer
D.
Oscillatory motion inside the cell
Correct Answer:
Sliding motion along the potentiometer wire
Explanation:
The jockey is designed to slide along the potentiometer wire and make contact at different positions.
9. What does a deflection of the galvanometer indicate when the jockey touches a point on the potentiometer wire?
A.
The jockey is not at the null point
B.
The potentiometer wire has no resistance
C.
The battery is disconnected
D.
The jockey has increased the emf of the cell
Correct Answer:
The jockey is not at the null point
Explanation:
A galvanometer deflection shows that a potential difference exists in the secondary circuit, so the jockey must be moved to another position.
10. What is the purpose of the sharp contact point of a potentiometer jockey?
A.
To make contact with a definite small point on the wire
B.
To cut the potentiometer wire into two parts
C.
To increase the thickness of the wire
D.
To store electrical charge
Correct Answer:
To make contact with a definite small point on the wire
Explanation:
The sharp contact allows the jockey to select a precise position on the potentiometer wire for accurate determination of the balance point.