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

The resistance is 100 ohms

The power has reduced 19%

Step-by-step explanation:

The formula for power is given as

`P=(V^2)/(R)`

Given data

power= 100 W

voltage= 100 V

Substituting into the power formula the resistance is

`100=(100^2)/(R) \\\\100*R=10000\\\\R= (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= (90^2)/(100) \\\\P= (8100)/(100) \\\\P= 81 watts`

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