Question

A generator has an emf of 420 V and internal resistance of 4000 $\Omega$. Its terminals are connected to a load of 800 $\Omega$. The voltage across the load would be :

• A. 220 V
  
• B. 70 V
  
• C. 110 V
  
• D. 84 V
  

Answer 1

The correct option is B 70 V

The generator can be thought a cell having $emf=420v$ and internal resistance $r=4000\Omega$

$R_L=$ Resistive load

$V_L=$ Voltage across resistive road

Apply Voltage division law,

$V_L=\frac{R_L}{Req}E$ Req: Equivalent resistance

Req : r + R_L$ (in series)

$=\frac{800}{4800}\times 420$ $\Rightarrow Req=4800\Omega$

$=\frac{420}{6}$

$V_L=70v$