Current Electricity and Electrical InstrumentHard
Question
In the adjacent circuit, AB is a potentiometer wires of length 40 cm no resistance per unit length 50Ω /m. As shown in the figure, the free end of an ideal voltmeter is touching the potentiometer wire. What should be the velocity of the jockey as a function of time so that reading in the voltmeter varies with time as (2sin πt)?
Options
A.(10 π sin πt) cm/s
B.(10 π cos πt) cm/s
C.(20 π sin πt) cm/s
D.(20 π cos πt) cm/s
Solution
Iwire = 
= 0.2A
potential difference across voltmeter,
⇒ 2 sin πt = 0.2 × 50 x -2 × 2 πcos πt = 10V
⇒ V = 20π (cosπt) cm/s
= 0.2Apotential difference across voltmeter,
⇒ 2 sin πt = 0.2 × 50 x -2 × 2 πcos πt = 10V
⇒ V = 20π (cosπt) cm/s
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