Question

A 90% efficient television uses 300 joules of electric energy per second. The amount of light the television produces is eight times the amount of sound. How much light and how much sound does the television produce each second?

Answer 1

A 90% efficient television produces 30 joules of sound energy and 240 joules of light energy per second.

Step-by-step explanation:

A 90% efficient television using 300 joules of electric energy per second means that 270 joules are being used per second for output (as light and sound), because 300 joules multiplied by 90% efficiency equals 270 joules. If the amount of light the television produces each second is eight times the amount of sound, we can represent the energy used for sound as 'x' and for light as '8x'. Therefore, x + 8x = 270 joules, which simplifies to 9x = 270 joules. Solving this, we find that x, the energy used for sound, is 30 joules per second. Consequently, the energy used for light is 8 times 30 joules, which is 240 joules per second.