JEE MAIN - Physics (2019 - 11th January Morning Slot - No. 17)
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 :
240 W
60 W
30 W
120 W
Explanation
In series condition, equivalent resistance is 2R
thus power consumed is 60W = $${{{\varepsilon ^2}} \over {2R}}$$
In parallel condition, equivalent resistance is R/2 thus new power is
P' = $${{{\varepsilon ^2}} \over {\left( {R/2} \right)}}$$
or P' = 4P = 240W
thus power consumed is 60W = $${{{\varepsilon ^2}} \over {2R}}$$
In parallel condition, equivalent resistance is R/2 thus new power is
P' = $${{{\varepsilon ^2}} \over {\left( {R/2} \right)}}$$
or P' = 4P = 240W
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