Current Electricity

Sliding contact of a potentiometer is in the middle of the potentiometer wire having resistance Rp=1 as shown in the figure. An external resistance of Re=2 is connected via the sliding contact. The electric current in the circuit is : [figure]

1. 1.35 A
2. 0.9 A
3. 1.0 A
4. 0.3 A

Answer

(3) 1.0 A

Solution

With the slider in the middle the wire splits into two halves of 0.5 ; Re is in parallel with one half.

[figure]

0.5 2= 0.5 22.5=0.4

Req=0.4+0.5=0.9

I= 0.90.9=1.0 A

Answer: (3)