Unit: MAGNETISM & ELECTRICITY
Year: 1990 Question#: 38
Question: A LAMP AND AN AMMETER ARE CONNECTED TO A SOURCE AS SHOWN. WHAT IS THE ELECTRICAL ENERGY EXPENDED IN THE LAMP IN 3.0 SECONDS?
(1 ) 50. J
(2 ) 150 J
(3 ) 50. W
(4 ) 150 W
What is this question really asking?
Explanation by: DIANA L.
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Answer 1
50. J
INCORRECT
Math or logic error. Try using the formula W=VIt return to top
Answer 2
150 J
CORRECT
You correctly used the formula W=VIt On top of that you realized that W is the symbol for both work done and energy used. return to top
Answer 3
50. W
INCORRECT
Looks like you used the formula for power not energy (work).
Try W=VIt return to top
Answer 4
150 W
INCORRECT
You got the right value but used the wrong units. Watts is the unit for power not energy. return to top
What's this question really asking?
How much work is done by the lamp in 3.0 seconds? return to top
