A servo voltage stabilizer restricts the voltage output to 220 V ± 1%. If an electric bulb rated at 220 V, 100 W is connected to it, what will be the minimum and maximum power consumed by it?

Question

Philoid · Accepted Answer

Given,

Output voltage, V = 220 V ± 1%

= 220 V ± 2.2 V

The resistance of a bulb that is operated at voltage V and consumes power P is given by Joule’s heating effect-

Putting the values in the above formula, we get

(a) We know that for minimum power to be consumed, output voltage should be minimum.

The minimum output voltage will be,

The current through the bulb,

Where

V is the voltage across the bulb

R is the resistance of the bulb

Putting the values in the above formula, we get

=0.45 A

Now, the power consumed by the bulb,

(b) For maximum power to be consumed, output voltage should be maximum.

The maximum output voltage,

The current through the bulb,

Power consumed by the bulb in this case is,