Question

The power supplied to a typical black-and-white television set is 90 W when the set is connected to 120 V. (a) How much electrical energy does this set consume in 1 hour? (b) A color television set draws about 2.5 A when connected to 120 V. How much time is required for it to consume the same energy as the black-andwhite model consumes in 1 hour?

Answer 1

Answer:

The electrical energy and time required for it to consume the same energy are $3.24\times10^{5}\ J$ and 18 min.

Explanation:

Given that,

Power = 90 W

Voltage V = 120 V

Current = 2.5

(a). We need to calculate the  amount of energy

Using formula of energy

$Q=pt$

Where, p = power

t = time

Put the value into the formula

$Q=90\times1$

$Q=90\times3600$

$Q=3.24\times10^{5}\ J$

(b). We need to calculate the  power

Using formula of power

$P=V\times I$

Where, I = current

V = voltage

Put the value into the formula

$P=120\times2.5$

$P=300\ W$

We need to calculate the time

Using formula of time

$t= \dfrac{Q}{P}$

Put the value into the formula

$t=\dfrac{3.24\times10^{5}}{300}$

$t=1080\s$

$t=\dfrac{1080}{60}=18\ min$

Hence, The electrical energy and time required for it to consume the same energy are $3.24\times10^{5}\ J$ and 18 min.