Question

While doing the experiment of copper voltmeter, in which of the following cases, more amount of copper gets deposited at cathode?

• A. 2 amperes of electric current is passed for 30 minutes
• B. 4 amperes of electric current is passed for 20 minutes
• C. 0.5 amperes of electric current is passed for 80 minutes
• D. 1.5 amperes of electric current is passed for 30 minutes

Answer 1

The correct option is B 4 amperes of electric current is passed for 20 minutes

Amount of copper ($W$) deposited on cathode is directly proportional to the product of electric current flowing and the time of operation.

$\therefore$ $W\propto It$

$⟹$ $W=zIt$ where $z$ is constant and known as electrochemical equivalent

(A) : $W_A=z\left(2\right)(30\times 60)=3600z$

(B) : $W_B=z\left(4\right)(20\times 60)=4800z$

(C) : $W_c=z\left(0.5\right)(80\times 60)=2400z$

(B) : $W_D=z\left(1.5\right)(30\times 60)=2700z$

Thus more amount of copper gets deposit at cathode in experiment B.