An electric lamp rated 60\,\text{W} operates normally when connected to a 240\,\text{V} ma… — JAMB UTME

An electric lamp rated $60\,\text{W}$ operates normally when connected to a $240\,\text{V}$ mains supply. What is the electric current drawn by the lamp?

$0.25\,\text{A}$ Answer
B
$4.0\,\text{A}$
C
$2.5\,\text{A}$
D
$14\,400\,\text{A}$

Answer

The electric current drawn by the lamp is

0.25\,\text{A}

Electric power is defined by the formula

P = IV

, where

P

is power in watts,

I

is current in amperes, and

V

is potential difference in volts. Rearranging to solve for current yields

I = \frac{P}{V}

. Substituting

60\,\text{W}

for power and

240\,\text{V}

for voltage gives

I = \frac{60}{240} = 0.25\,\text{A}

Step-by-Step Solution

Identify given parameters and state the electric power formula.

Power

P = 60\,\text{W}

and voltage

V = 240\,\text{V}

. Power is related to current and voltage by

P = IV

Electric power dissipated by a component is the product of current and voltage across it.

Rearrange the formula to solve for current

I

I = \frac{P}{V}

Making current

I

the subject of the equation.

Substitute the values into the formula and solve.

I = \frac{60\,\text{W}}{240\,\text{V}} = 0.25\,\text{A}

Dividing

60

240

gives

0.25

amperes.

Key Concept

Relationship between Electrical Power, Voltage, and Current

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