BITSAT 2018 Paper

As the two cells oppose each other hence,the effective emf in closed circuit is 15 – 10 = 5V and net resistance is 1 + 0.6 = 1.6 Ω (because in the closed circuit the internal resistance of two cells are in series.
Current in the circuit I =

effective‌emf

total‌resistance

=

5

1.6

A
The potential difference across voltmeter will be same as the terminal voltage of either cell.Since the current is drawn from the cell of 15 V
∴ V1 = E−1−Ir1 = 15 -

5

1.6

× 0.6 = 13.1 V