7A

YOUR ANSWER: 25 watts.

Right. P is still equal to E x I.

What is the power consumption in the circuit?

10 watts.

frame 9A

100 watts.

frame 6C

7B

YOUR ANSWER: P = E x I.

Well, at least you remembered the basic power formula.

But you were asked, which formula you would use to solve for power, if voltage and

resistance of the circuit were known.

We just gave you the formula on the preceding page: P = E2

R

Here is an explanation as to how we arrive at this formula. P = E x I in our basic power

formula. I = E in Ohm's law. We car, substitute E for "I" in the basic power

R

R

law; thus, P = E x F or P =E2.

R

R

Now, go back to frame 9A and select the correct answer.

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