Q. A current of 1.5 A flows through a copper voltmeter. The thickness of copper deposited on the electrode surface of area 50 $cm^{2}$in 20 min is (density of Cu=9000 $kgm^{- 3};ECE\ of\ Cu = 3.3 \times 10^{- 7}kgC^{- 1})$
A) $1.3 \times 10^{- 4}\ $m
B) $1.3 \times 10^{- 5}\ $m
C) 2.6$\ \times 10^{- 4}$ m
D) 2.6 $\times 10^{- 5}$ m
Explanation
(b) $m = zit$
If V is the volume, then V$= \frac{m}{\rho} = \frac{zit}{\rho}$
Thickness $= \frac{zit}{A\rho} = \frac{3.3 \times 10^{- 7} \times 1.5 \times 20 \times 60}{50 \times 10^{- 4} \times 9000}$
Thickness $= 1.3 \times 10^{- 5}$m
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.