Question

A cell of emf 2 volt and internal resistance 0.1 ohm is connected to 3.9 external resistance what will be the potential difference across the terminals of the cell

Answer 1

Final Answer : 1.95V

1) Potential Difference across terminal of a cell,

V = E - I r

where

E = EMF of cell =2V

r = internal resistance =0.1ohm

i = current in circuit.

R = External Resistor

Steps :

1) Cell and External resistor are connected directly,

=> R(eq) = r + R

=0.1 + 3.9 = 4.0 oh m

2) Current in circuit,

I = E / R(eq)

= 2/4.0 = 1/2 =0.5 A

3) Potential Difference across terminal of a cell,

V = E - Ir

= 2 - 0.5 *0.1

= 1.95 V.