Question

two cells of emf 1v,2v and internal resistance 2ohm and 1ihm respectively are connected in series and parallel what should be the external resistance in the circuit show that the current through the resistance be the same in both cases? in whcich case more heat is generated in the cells?

Answer 1

Explanation:

ANSWER

given data E

1

=IV E_2 = 2V $$

R

1

=2nR

2

=1n

→ if connected in series

effective emt = E

1

+E

2

=1+223v

effective internal resistance = R

1

+R

2

=2+1=3n

current through circuit =

R

V

=

3+r

3

........1

where r in internal resistance

→ it connected in parellel

effective emt = 2V

effective resistance = R

1

∣∣R

2

=

2

1

+

1

1

=

3

2

r

current through external resistance =

3

2

+r

2

in two case current in same

∴

3+r

3

=

3

2

+r

2

→(

3

2

+r)3=6+2r

2+3r=6+2r

4=4n

∴ external resistance to be connect in

r=4n