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
An ammeter and a voltmeter are used to measure the current in a...
An ammeter and a voltmeter are used to measure the current in a conductor and the potential difference across its terminals. Both meters draw negligible currents. The ammeter is perfectly accurate, whereas the voltmeter possesses a zero error (meaning it fails to read zero when no potential difference is present). Determine the zero error if the readings under two distinct conditions are , and , .
Options
- A
- B
- C
- D
Correct answer
A.
Step-by-step solution
Let be the resistance of the conductor and be the zero error of the voltmeter.
The true potential difference across the conductor is given by Ohm's law as .
The voltmeter reading is .
Using the given readings, we can write two equations:
Subtracting the first equation from the second yields:
Substituting the value of into the first equation:
The true potential difference across the conductor is given by Ohm's law as .
The voltmeter reading is .
Using the given readings, we can write two equations:
Subtracting the first equation from the second yields:
Substituting the value of into the first equation: