Question

In the circuit shown, the resistances are given in ohms and the battery is assumed ideal withh emf equal to 3.0 volts.
Q. The current passing through 3 V battery is
A. 10 mA
B. 30 mA
C. 40 mA
D. 60 mA

Answer 1

Correct Answer - C

The equivalent circuit can be redrawn as shown in figure 1. From figure 1 it is obivious that power dissipated by `R_(1)` is maximum. Potential difference across
`R_(2)` is `=(25)/(25+50)xx3` volt `=1` volt
Therefore potential difference across `R_(3)` or
`R_(4)=(20)/(20+30)xx1` volt `=0.4` volt ltbr. the equivalent resistance of circuit across the cell
is `50+25=75` ohms
Therefore current through cell is
`(3)/(75)xx1000` mA `=40` mA