Question

Every electrical appliance like an electric bulb,radio or fan has a label or engraved plate on it which tells us the voltage and electrical power consumed by it.The power rating of an electrical appliance tells us the rate at which electrical energy is consumed by the appliance.For example ,a power rating of 100 watts on the bulb means that it will consume electrical energy at the rate of 100 joules per second.If we know the power P and voltage V of an electrical appliance,then we can very easily find out the current I drawn by it. This can be done by using the formula: P=V*I.

(i) An electric bulb is rated 220V and 100W. What is the resistance of the bulb?

448 Ohm

488 Ohm 

484 Ohm

482 Oh​

Answer 1

Answer:

488

Explanation:

P=VI

I=0.45a

R=V/I

R=220/0.45

=488Ohms

Answer 2

The required resistance of the bulb is 484 ohm.

Given :

The rating of an electric bulb is 220V and 100W.

To find :

The resistance of the bulb

Solution:

We can find the solution to this question in the following way.

We know that the relation among the parameters power, voltage, and current is as follows.

$Power = Voltage\times Current$

We can find the current rating of the electric bulb using the above formula.

Thus the current rating of the electric bulb

$=\frac{Power}{Voltage}\\=\frac{100}{220}\\=\frac{5}{11} ampere$

We know that the relation among the parameters resistance, voltage, and current is as follows.

$Voltage = Resistance\times Current$

We can find the resistance of the electric bulb using the above formula.

Thus the resistance of the electric bulb

$=\frac{Voltage}{Current}\\=\frac{220}{\frac{5}{11} }\\=484 ohm$

The required resistance of the bulb is 484 ohm.

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