Question

The current through a 60W lamp rated for 250V is
A) 0.24A
B) 4.2A
C) 0.5A
D) 6A

Answer 1

In this question, power and voltage is given we have to find out the value of current. For this we use the formula which relates the power, voltage and current i.e. $P = VI$ , on substituting the values we can easily find the value of current.

Complete step by step solution
As, it is given that
Power of the lamp is $P = 60W$
And the voltage across the lamp is $V = 250V$
We have to find the value of current.
For this, we know that the power is equal to the product of voltage and current. Therefore, we can write it as $P = VI$
P is power of the lamp and V is the voltage across the lamp and I is the current passing through the lamp.
We can write above formula as $I = \dfrac{P}{V}$
Now, substitute the given values of P and V in above equation, we get
$\Rightarrow I = \dfrac{{60}}{{250}}$
$\Rightarrow I = 0.24A$
Hence, the current through a 60W lamp of rated 250V is 0.24A.
Therefore, option A is correct.

Note:
Electrical power is defined as the rate of consumption of energy or the rate of doing work i.e. $power = \dfrac{{work}}{{time}}$
And we also know that the work done by current I when it flows in potential V at time t is $W = VIt$
On substituting this value in the formula of power, we get
$\Rightarrow P = \dfrac{{VIt}}{t} = VI$
In this way we can derive the expression of power.