Question

In a copper voltmeter experiment, a current is decreased to one-forth of the initial value but it is passed for four times the earlier duration. Amount of copper deposited will be

• A. same
• B. one-forth the previous value
• C. Four times the previous value
• D. $(1/16{)}^{th}$ of the previous value

Answer 1

The correct option is A same

Mass of the substance deposited due to a current I passed through them for a time t, is given by

$m=ZIt$.........(1)

When a current is decreased to one-forth of the initial value i.e. $I=\frac{1}{4}I$ and is passed for four times the earlier duration i.e. $t=4t$, then

$m^{\prime }=Z\left(\frac{1}{4}I\right)\left(4t\right)$

$m^{\prime }=ZIt$ ...........(2)

From (1) and (2),

$m^{\prime }=m$

Hence, amount of copper deposited is same in both conditions.