Question

A bulb of rating 100W,220 volt is connected to a supply source of 110V. If the power consumption required from source is 100 W, then how many identical bulbs are required to be connected in the circuit?

Answer 1

A bulb of rating 100W,220 volt is connected to a supply source of 110V. If the power consumption required from source is 100 W, then how many identical bulbs are required to be connected in the circuit?

it is 3

Answer 2

Answer:

The number of bulb is 4.

Explanation:

Given that,

Power = 100 w

Voltage = 220 V

We need to calculate the resistance

Using formula of power

$P = \dfrac{V^2}{R}$

$R=\dfrac{V^2}{P}$

Put the value into the formula

$R=\dfrac{220^2}{100}$

$R=484\ \Omega$

If this bulb connected to 110 V power supply

Power consumed by one bulb

Using formula of power

$P=\dfrac{V^2}{R}$

$P=\dfrac{110\times110}{484}$

$P=25\ W$

We need to calculate the number of bulb for 100 W power consumption

Using formula of power consumption

$n=\dfrac{Power}{Power\ consume}$

$n=\dfrac{100}{25}$

$n=4$

Hence, The number of bulb is 4.