Question

If this battery is connected to a 15$\Omega$ resistor R whose emf is 40V and an internal resistance of 5$\Omega$. Calculate the voltage drop across R.

• A. $10V$
• B. $30V$
• C. $40V$
• D. $50V$
• E. $70V$

Answer 1

The correct option is B $30V$

Given : $E=40V$ $R=15\Omega$ $r=5\Omega$

Current through the circuit $I=\frac{E}{R+r}=\frac{40}{15+5}=2$ $A$

$\therefore$ Voltage drop across R $V_R=IR=2\times 15=30$ V