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Two equal resistances 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

Asked in JEE Main 11th Jan 1st Shift 2019 · Heating and power in resistors

Answer: (1) 240 W

Step-by-step solution

Series: Rₛ=2R; parallel: Rₚ=R/2.

At fixed battery voltage, P=(V²)/(R_eq), so (Pₚ)/(Pₛ)=(Rₛ)/(Rₚ)=(2R)/(R/2)=4.

Pₚ=4×60=240 W.

Why the other options are wrong

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