Question

for a heater rated at 4kW and 220v, calculate: 1. the current, 2. the resistance of the heater, 3. the energy consumed in 2 hours and 4. the cost if 1 kWh is priced at 50 paise

Answer 1

1. 18.18A
2. 12.1ohm
3.8kwh
4

Answer 2

Answer: (I). The current is 18.18 A, (II). the resistance of the heater is 12.1 ohm, (III). the energy consumed will be 8 kW/hr and (IV). The cost of 8 kW/hr will be 4 rupees.

Explanation:

Given that,

Power = 4 kW

Voltage = 220 v

(I). The current is

We know that, the power is the product of current and voltage.

$P = I\times V$

$I = \dfrac{P}{V}$

$I = \dfrac{4\ kW}{220\ V}$

$I = 18.18\ A$

(II). The resistance of the heater is

Using ohm's law

$V = I\times R$

$R = \dfrac{V}{I}$

$R = \dfrac{220}{18.18}$

$R = 12.1\Omega$

(III). The energy consumed in 2 hours

$E = Pt$

$E = 4\times2$

$E = 8\ kW/hr$

(IV). If the cost of 1 kW/hr is 50 paise

Then, the cost of 8 kW/hr will be

The cost of 8 kW/hr $= 8\times 50$

The cost of 8 kW/hr will be 4 rupees.