Question

The power rating of a 400-Ω resistor is 0.800 W.(a) What is the maximum voltage that can be applied across this resistor without damaging it? Use three significant figures in your answer.

Answer 1

Answer:

$V=17.9\ Volt$

Explanation:

Joule's Law in Electricity

The Joule's law allows us to calculate the power dissipated in a resistor of resistance R through which goes a current I.

$P=I^2R$

The relation between the voltage and the current is given by Ohm's law:

$V=RI$

Solving for I and replacing int the first equation

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

Solving for V

$V=\sqrt{PR}$

$V=\sqrt{0.8\cdot 400}=17.9$

$\boxed{V=17.9\ Volt}$