Question

An electric heater and a fan marked 1000 W, 220 V and 100 W, 220 V respectively. The resistance of fan is

• A. equal to that of heater.
• B. greater than that heater.
• C. less than that of heater.
• D. zero.

Answer 1

Answer: (B)

greater than that heater.

Here, an electric heater and a fan marked 1000 W, 220 V and 100 W, 220 V respectively.
Hence, the resistance of fan is
$R_f=\frac{(V_f{)}^2}{P_f}$ ........(since, $P=\frac{V^2}{R}$)
$R_f=\frac{(220{)}^2}{100}=484\Omega$ ........................(1)
And
$R_h=\frac{(V_h{)}^2}{P_h}$
$R_h=\frac{(220{)}^2}{1000}=4.84\Omega$ ......................(2)
From (1) and (2), the resistance of fan is greater than that of heater.