Question

A power of 100 W is delivered to a certain resistor when the applied voltage is 100 V. Find the resistance. Suppose that the voltage is reduced by 10% to 90 V. By what percentage is the power reduced

Answer 1

Answer:

The resistance is 100 ohms

The power has reduced 19%

Explanation:

 The formula for power is given as

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

Given data

power= 100 W

voltage= 100 V

Substituting into the power formula the resistance is

$100=\frac{100^2}{R} \\\\100*R=10000\\\\R= \frac{10000}{100} \\\\R= 100 ohms$

The resistance is 100 ohms

Now the power has been reduced by 10% (from 100 to 90V)

the power is

$P= \frac{90^2}{100} \\\\P= \frac{8100}{100} \\\\P= 81 watts$

The power has reduced 19% from 100 watt to 81 watt