In an experiment of calibartion of voltmeter, a standard cell of emf `1.1 V` is balanced against `440 cm` of potentiometer wire. The potentilal difference across the ends of a resistance is found to balance against `220 cm` of the wire. The corresponding reading of voltmeter is 0.5 volt. Find the error in the reading of voltmeter.

Answer

` - 0.05 V`

Explanation

Potential gradent `K = (11)/(440) = 0.0025 V//cm`
potential difference across `R`
`= 0.0025 xx 220 = 0.550V`
Error in voltmeter reading = reading in voltmeter - reading of potentiometer
`= 0.5 - 0.550 = - 0.05 V`