Abattery is connected across a variable external resistance R When the current is 6A, the terminal potential difference is - Physics - Current Electricity

Question

Abattery is connected across a variable external resistance R
When the current is 6A, the terminal potential difference is 8 4V ;
when the current is 8A, the terminal potential difference is 7 2V
Find theEMF and the internal resistance

Himanshu · Accepted Answer

Let E be the emf of the cell and r be the
internal resistance
Therefore, 8 4 = E - 6r and 7 2 = E -
8r
8 4 - 7 2 = 8r - 6r = 2r
Or, 1 2 = 2r
Therefore, r = 0 6 ohms and E = 7 2 +
8r = 12 Volts

Abattery is connected across a variable external resistance R. When the current is 6A, the terminal potential difference is 8.4V ; when the current is 8A, the terminal potential difference is 7.2V. Find theEMF and the internal resistance.