science question help?

Question

if a 60W light bulb in a bedside lamp is only 20 percent efficient in converting electric energy into light energy, how much joules of light energy does the light bulb produce each time?

the W stands for watts
pls help me i is my homework thank you

Answer 1

1 Watt-Hour = 3600 Joules

Knowing That ^...

60W x 0.20 = 12W

12W x 3600 J = 43,200 Joules/Hour


Why * x 0.20 * ? Because you have to find 20% of 60.
Have Fun!

Answer 2

All of the 60W is converted into light, but only 20% of that light is visible.
1 W = 1 joule/second
20% = 20/100
20*60/100 = 12 joules per second

Answer 3

Depends on how long it is on. It produces light at the rate of 12 watts. A watt-second is one joule, so it is producing 12 joules per second of light energy while consuming 60 joules per second of electrical energy.

Answer 4

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