Question

Three equal resistors connected in series across a source of e.m.f together dissipate 10W power. The power dissipated if the same resistors are connected in parallel across the same source of emf is

• A. 1) 10W
• B. 2) 30W
• C. 3) 90W
• D. 4) 60W

Answer 1

The correct option is C 3) 90W

Case 1 :-

$P=\frac{E^2}{3R}=10W$

Case 2:-

$P=\frac{E^2}{\frac{R}{3}}$

$=\frac{9E^2}{3R}$

$P=9\times 10=90W$