Question

How many cells each of e.m.f. 1.5 V and internal resistance 0.5 Ω , should be joined in series to get a current of 2 A in an external circuit with a 30 V difference in potential across the terminals of the battery of cells.​

Answer 1

Explanation:

Equivalent resistance of r

1

and r

2

, r

eq

=

1+2

1×2

=0.66Ω

Equivalent emf of E

1

and E

2

, E

eq

=[

r

1

E

1

+

r

2

E

2

]r

eq

⟹ E

eq

=[

1

12

+

2

13

]×0.66=12.33 V

Potential across R, V

R

=

R+r

eq

R

E

eq

⟹ V

R

=

10+0.66

10

×12.33=11.57 V