Physics Review Question

Unit: Electricity
Year: 1996 Question#: 36
Question: If the potential drop across an operating 300. - watt floodlight is 120 volts, what is the current through the floodlight?

(1 ) 0.40 A
(2 ) 2.5 A
(3 ) 7.5 A
(4 ) 4.8 A

What is this question really asking?




Explanation by: Alon B

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Answer 1
0.40 A

INCORRECT

This answer is incorrect. try and use the formula for Power P=VI return to top























Answer 2
2.5 A

CORRECT

This answer is correct. If you plug in the numbers for the Power formula you will find that the current equals 2.5 A.
P=VI
300w = 120v * I
300w / 120v = I
I=2.5 A return to top



























Answer 3
7.5 A

INCORRECT

This answer is incorrect because after pluging in the numbers, in the equation, the answer will not be 7.5 A. Try using the Power formula. P=VI return to top


























Answer 4
4.8 A

INCORRECT

This answer is also incorrect because afeter pluging in the numbers, in the equation, the answer will not be 4.8 A. Try using the Power formula. P=VI return to top


























What's this question really asking?

This question is testing to see if you know the units of power, current, and electric potential difference. It also tests to see if you know the correct formulas to use once you find the variables. return to top

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