How much power (in watts) is dissipated by a resistor when an RMS current of 1.3 amperes passes through the resistor with an RMS voltage drop of 30 volts?

Question

I've tried using the formula RMS current^2 X the resistor but it did not work. I am not sure how to solve this one.

Answer 1

We can use the power law and ohms law.

 

 

Ohm's Law

 

V = IR

 

where:

V = voltage

I = current

R = resistance

 

 

Power Law

 

P = VI

 

where:

P = power

V = voltage

I = current

 

When we solve problems like these, it is great strategy to write down what is given.

 

I = 1.3 A

V = 30 volts

 

Knowing this, we can use the formulas to find what we need.

 

We can use Ohm's Law to find the resistance, since this value is not known.

 

R = V / I

R = 30 / 1.3

R = 23.08 ohms

 

Now, we can find the power using this value of R.  By the power law

 

P = VI

P = IRI

P = I²R

P = (1.3)²(23.08)

P = 39.01

 

The power is 39.01 Watts.