Question

5. If the current in an electric bulb is
increased by 3% at constant
resistance, the power is increased
by
(1)6 %(B) 1.5 % (C)3 % (D) 1 %​

Answer 1

The percentage of increase in power of an electric for  bulb with 3 % increase in current is 6%.Option (1 ) is correct.

Given:

The percentage of increase in current in an electric bulb is 3%.

To Find:

The percentage of increase in power of the electric bulb.

Solution:

An electric bulb consists of a filament with  some resistance.When current flows through it ,the electrical energy is converted into light energy.

The power across it is given by $P = I^{2} * R$

From this we can infer that,Power is directly proportional to the square of the current.

So if current increases, the power across the bulb also increases.

Let us assume that $\frac{change in current }{current} * 100 = x$  and $\frac{change in power}{power} * 100 =Y$.

Now ,let us formulate the change in power as,

$Y = 2 * x$  [Since R is constant].

Substituting the corresponding value we get,

$Y = 2 * 3$     [given ]

$Y =6 %$ %

Therefore ,the percentage of increase in power is 6%.That is option (1) is correct.

#SPJ1