Question

a lamp has a power of 120 w and is left on for 24 hours. a television has a power of 350 w and is left on for 3 hours. which statement correctly compares the energy used by these devices?

a. the television uses 6,588,000 j less than the lamp.
b. the television uses 10,368,000 j more than the lamp.
c. the television uses 3,780,000 j less than the lamp.
d. the television uses 2,356,000 j more than the lamp.

Explanation:

Step1: Calculate energy used by lamp

Energy formula \(E = P\times t\). Convert time \(t_{lamp}=24\ h = 24\times3600\ s = 86400\ s\), \(P_{lamp}=120\ W\). Then \(E_{lamp}=120\times86400 = 10368000\ J\)

Step2: Calculate energy used by television

Convert time \(t_{TV}=3\ h=3\times3600\ s = 10800\ s\), \(P_{TV} = 350\ W\). Then \(E_{TV}=350\times10800=3780000\ J\)

Step3: Find the difference

\(\Delta E=E_{lamp}-E_{TV}=10368000 - 3780000=6588000\ J\)

Answer:

A. The television uses 6,588,000 J less than the lamp.