Question

24. Calculate the current passing through a bulb rated
60 W, 240 V when it is connected to a 240-V
power supply.
​

Answer 1

✬ Current = 0.25 A ✬

Step-by-step explanation:

Given:

• Power of bulb is 60W.
• Voltage is 240V.

To Find:

• How much current is passing ?

Formula to be used:

• P = V $\times$ I

Solution: Here we have

• P = 60 W
• V = 240 V
• I = ?

Putting the values on formula

$\implies{\rm }$ P = VI

$\implies{\rm }$ P/V = I

$\implies{\rm }$ 60/240 = I

$\implies{\rm }$ 6/24 = I

$\implies{\rm }$ 1/4 = I

$\implies{\rm }$ 0.25 A = I

Hence, 0.25 Ampere current is passing through the bulb.

_____________________

[ Let's see a long method ._. ]

Formula to be used:

• P = V²/R
• V = IR

Solution: Here we have

• P = 60 W
• V = 240 V
• I = ?
• R = ?

Put the values on first formula

$\implies{\rm }$ P = V²/R

$\implies{\rm }$ 60 = 240² / R

$\implies{\rm }$ 60R = 57600

$\implies{\rm }$ R = 57600/60

$\implies{\rm }$ R = 960 ohms

Using the second formula for finding current

$\implies{\rm }$ V = IR

$\implies{\rm }$ 240 = I $\times$ 960

$\implies{\rm }$ 240 = 960I

$\implies{\rm }$ 240/960 = I

$\implies{\rm }$ 24/96 = I

$\implies{\rm }$ 1/4 = I

$\implies{\rm }$ 0.25 A = I

Hence, current is 0.25 A.

Answer 2

Given ,

Electric power (P) = 60 W

Potential difference (V) = 240 volt

We know that ,

Electric power is defined as the product of potential difference and current

$\boxed{ \tt{Electric \: power \: (P) = VI}}$

Thus ,

60 = 240 × I

I = 60/240

I = 0.25 Amp

Hence ,

• The current passing through a bulb rated is 0.25 Amp