Same chapter3 marksDifficulty: Medium
Three resistors of 6 Ω each are joined in parallel and the combination is connected across a 12 V battery of negligible internal resistance. Find the current drawn.
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3 marksDifficulty: Medium
State the principle of a potentiometer and one advantage it has over a voltmeter.
Original Khojo Papers practice question — not from a past board paper.
Answer
A potentiometer works on the principle that the potential difference across a uniform wire carrying a steady current is proportional to the length of the wire. At the balance point it draws no current from the cell being measured, so it gives the true emf, whereas a voltmeter always draws some current and therefore reads the terminal potential difference, which is less.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
It is effectively an infinite-resistance voltmeter.
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