Q. If two wires having resistances $R$ and $2R$ both are joined in series and in parallel, then ratio of heat generated in this situation, applying the same voltage is
A) 2 :1
B) 1 :2
C) 2 :9
D) 9 :2
Explanation
(c) Heat $\ H = \frac{V^{2}t}{R} \Rightarrow H \propto \frac{1}{R}\ \ \ \ \ \ \ \ \ $[If$\ V,\ t\ $constant]
$\Rightarrow \frac{H_{S}}{H_{P}} = \frac{R_{P}}{R_{S}} = \frac{\left( \frac{R \times 2R}{3R} \right)}{(R + 2R)} = \frac{2}{9}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.