Question

c) gavin leaves the lights running for 5 hours. convert the 20ma to amperes, and multiply this by the number of seconds that they are running for. this will tell us how many \coulombs\ of charge run through the leds in the day.

Explanation:

Step1: Convert mA to Amperes

$20\ \text{mA} = 20 \times 10^{-3}\ \text{A} = 0.02\ \text{A}$

Step2: Convert hours to seconds

$5\ \text{hours} = 5 \times 3600\ \text{seconds} = 18000\ \text{seconds}$

Step3: Calculate charge (Q=I×t)

$Q = 0.02\ \text{A} \times 18000\ \text{s}$

Answer:

$360\ \text{Coulombs}$