Q. $A$ and $B$ are two square plates of same metal and same thickness but length of $B$ is twice that of $A.$ Ratio of resistances of $A$ and $B$ is
A) 4 : 1
B) 1 : 4
C) 1 : 1
D) 1 : 2
Explanation
(c) $R_{A} = \frac{\rho l}{l \times t} = \frac{\rho}{t}$ and $R_{B} = \frac{\rho \times 2l}{2l \times t} = \frac{\rho}{t}\ i.e.\frac{R_{A}}{R_{B}} = 1\ :1$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.