A closed box has two metal terminals a and b The inside of t

A closed box has two metal terminals a and b. The inside of the box contains an unknown emf 8 in series with a resistance R. When a potential difference of 22.0 V is maintained between terminal a and terminal b, there is a current of 1.50 A between the terminals a and b. If this potential difference is reversed, a current of 1.90 A in the reverse direction is observed. Find epsilon and R.

Solution

In forward direction,

The net emf, ( E + 22 ) V

So, net current = (E+22)/R = 1.9 A ----------- (1)

In reverse direction,

net current = (22 - E)/R = 1.5 A ---------- (2)

Solving these two equations ,

we get

E = 2.6 V <--------answer

R = 12.9 ohm <-----------answer