Concepts Of Physics MCQ Edition [Volume 2]
- Exam
- Concepts Of Physics MCQ Edition [Volume 2]
- Subject
- Physics
- Chapter
- Electric Current in Conductors
Concepts Of Physics MCQ Edition [Volume 2] · Physics · Electric Current in Conductors
In the circuit depicted in the figure, the battery has an...
In the circuit depicted in the figure, the battery has an electromotive force of and an internal resistance of . The external resistance is . The resistances of the ammeter and the voltmeter are and , respectively. Determine the readings of the ammeter and the voltmeter in the given switch configuration.

Options
- A,
- B,
- C,
- D,
Correct answer
B. ,
Step-by-step solution
Based on the given circuit diagram, the switch connects the voltmeter in parallel with the external resistance only.
First, we calculate the equivalent resistance of the parallel combination of the resistor and the voltmeter :
Substituting the given values (, ):
This parallel combination is in series with the ammeter () and the internal resistance of the battery (). The total equivalent resistance of the circuit is:
The total current flowing through the main circuit, which is also the reading of the ammeter, is given by Ohm's law:
The voltmeter measures the potential difference across the parallel combination . This voltage is:
Therefore, the ammeter reads and the voltmeter reads .
Answer: ,
First, we calculate the equivalent resistance of the parallel combination of the resistor and the voltmeter :
Substituting the given values (, ):
This parallel combination is in series with the ammeter () and the internal resistance of the battery (). The total equivalent resistance of the circuit is:
The total current flowing through the main circuit, which is also the reading of the ammeter, is given by Ohm's law:
The voltmeter measures the potential difference across the parallel combination . This voltage is:
Therefore, the ammeter reads and the voltmeter reads .
Answer: ,