Question

in figure shown the reading of ammeter is I A 1 reading of voltmeter is 1.5 volt find EMF and r

Answer 1

EMF is also known as the potential difference across the terminal of the battery.

So, we can write EMF as Voltage
I. e; EMF=Voltage

The voltage is equal to voltage of first battery + voltage of second battery + voltage of third battery + voltage of fourth battery
I. e; Voltage=V1+V2+V3+V4
Voltage= 6+3+2+1.5
Voltage=12.5 volts.
Therefore, EMF = 12.5 volts

Now, we know that:

V=IR
V/I=R
12.5/1=R
R=12.5 ohm