AMU Engineering 2017 solved paper Solved Paper

Let emf of a cell =ε
and its internal resistance =r
Power consumed by any resistance R is given by
P=

V2

R

For series combination, V=2ε and R=2r
∴Ps=

(2ε)2

2r

=

2ε2

r

For parallel combination, V=ε and R=

r

2

∴Pp=

ε2

r 2

=

2ε2

r

Hence,

Ps

Pp

=

2ε2

r

×

r

2ε2

=

1

1