Final answer:
A 100-watt light bulb with an efficiency of 95% will add 72000 Joules of thermal energy to the auditorium after being left on for 4 hours.
Step-by-step explanation:
To calculate how much thermal energy a 100-watt light bulb with an efficiency of 95% will add to an auditorium after being left on for 4 hours, we use the formula for power and energy conversion:
P (Power) = 100 W (watts)
t (Time) = 4 hours = 4 × 3600 seconds = 14400 seconds
Efficiency = 95%
Energy (E) = P × t × Efficiency
Since only the inefficient part converts to thermal energy, we calculate:
Inefficient energy = P × t × (1 - Efficiency)
E = 100 W × 14400 s × (1 - 0.95)
E = 100 W × 14400 s × 0.05
E = 72000 Ws or Joules (since 1 Ws = 1 J)
Therefore, the light bulb will add 72000 Joules of thermal energy to the auditorium.