Two equal resistance when connected in series to a battery, consume electric power of 60 W. If these resistances are now connected in parallel combination to the same battery, the electric power consumed will be :

Question

Two equal resistance when connected in series to a battery, consume electric power of 60 W. If these resistances are now connected in parallel combination to the same battery, the electric power consumed will be : (A) 60 W (B) 240 W (C) 30 W (D) 120 W

Tardigrade Admin · Accepted Answer

In series condition, equivalent resistance is 2R thus power consumed is 60W = ( ε2/2R) In parallel condition, equivalent resistance is R/2 thus new power is P' = (ε2/(R / 2)) or P' = 4 P = 240 W

Q. Two equal resistance when connected in series to a battery, consume electric power of $60 W$ . If these resistances are now connected in parallel combination to the same battery, the electric power consumed will be :

60 W

240 W

30 W

120 W

In series condition, equivalent resistance is 2R
thus power consumed is 60W $= \frac{ε ^{2}}{2 R}$
In parallel condition, equivalent resistance is R/2 thus new power is
$P^{'} = \frac{ε ^{2}}{( R /2 )}$
or $P^{'} = 4 P = 240 W$

Q. Two equal resistance when connected in series to a battery, consume electric power of 60W. If these resistances are now connected in parallel combination to the same battery, the electric power consumed will be :