physics : class12 Driver Cell : Potentiometer : Current Electricity MCQ Questions and Answers
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Driver Cell
MCQ questions and answers.
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MCQ Questions
1. What is the main function of the driver cell in a potentiometer circuit?
A.
To produce a potential gradient along the potentiometer wire
B.
To measure the resistance of the wire
C.
To detect current in the galvanometer
D.
To increase the length of the potentiometer wire
Correct Answer:
To produce a potential gradient along the potentiometer wire
Explanation:
The driver cell sends current through the potentiometer wire and establishes a potential gradient along it.
2. The driver cell in a potentiometer is connected across the:
A.
Galvanometer only
B.
Potentiometer wire
C.
Jockey only
D.
Unknown resistance only
Correct Answer:
Potentiometer wire
Explanation:
The driver cell is connected across the potentiometer wire so that current flows through the wire and produces a potential gradient.
3. Which type of cell is generally used as the driver cell in a potentiometer?
A.
A source of steady emf
B.
A discharged cell
C.
A cell with zero emf
D.
A cell used only as a detector
Correct Answer:
A source of steady emf
Explanation:
The driver cell must supply a steady emf to maintain a stable current and potential gradient in the potentiometer wire.
4. If the driver cell is removed from a potentiometer circuit, what happens to the potential gradient along the wire?
A.
It becomes zero
B.
It becomes infinite
C.
It remains unchanged
D.
It reverses automatically
Correct Answer:
It becomes zero
Explanation:
Without the driver cell, no current flows through the potentiometer wire, so no potential gradient is produced.
5. The positive terminal of the driver cell should be connected to which end of the potentiometer wire?
A.
The end connected to the jockey
B.
The end connected to the galvanometer
C.
The end chosen as the higher-potential end
D.
Any end without making a connection
Correct Answer:
The end chosen as the higher-potential end
Explanation:
The positive terminal of the driver cell is connected to one end of the wire to establish a definite direction of potential fall along the wire.
6. What does the driver cell provide to the potentiometer wire?
A.
A uniform potential gradient
B.
A magnetic field
C.
A mechanical force
D.
A sound signal
Correct Answer:
A uniform potential gradient
Explanation:
When the wire is uniform and carries steady current from the driver cell, the potential drop per unit length is approximately uniform.
7. Why should the driver cell have sufficient emf in a potentiometer?
A.
To produce a measurable potential drop along the wire
B.
To prevent the wire from having resistance
C.
To eliminate the need for a jockey
D.
To make the galvanometer act as a battery
Correct Answer:
To produce a measurable potential drop along the wire
Explanation:
A driver cell with sufficient emf produces an adequate potential gradient for measurements using the potentiometer wire.
8. A rheostat used with the driver cell in a potentiometer helps to:
A.
Control the current through the potentiometer wire
B.
Change the chemical composition of the cell
C.
Measure the emf of the driver cell directly
D.
Replace the potentiometer wire
Correct Answer:
Control the current through the potentiometer wire
Explanation:
The rheostat adjusts the current supplied by the driver cell and therefore helps control the potential gradient along the wire.
9. The current supplied by the driver cell should ideally remain:
A.
Steady
B.
Zero at all times
C.
Random
D.
Increasing continuously
Correct Answer:
Steady
Explanation:
A steady current from the driver cell is needed to maintain a constant potential gradient during the experiment.
10. If the polarity of the driver cell is reversed, the direction of the potential gradient along the potentiometer wire will:
A.
Reverse
B.
Remain exactly the same
C.
Become independent of current
D.
Disappear permanently
Correct Answer:
Reverse
Explanation:
Reversing the driver cell reverses the direction of current through the potentiometer wire and hence reverses the potential gradient.