Question

What is the percentage efficiency of a 70W bulb that produces 210J of light energy over a minute?

Answer 1

Step-by-step explanation:

Given:

P = 70 W - Lamp power

A = 210 J - Lamp energy

t₀ = 1 min = 60 s - Time

_________

ε - The percentage efficiency

t = A / P = 210 / 70 = 3 s

ε = t / t₀ = 3 / 60 = 0.05 or ε = 0,05·100% = 5%

Answer 2

5%

Step-by-step explanation:

here

power = 70w

output = 210 J

time = 1 mins = 60 secs

for total input we get

input energy = P*t

= 70*60 = 42000J

for the efficiency we know that

%efficiency = (total output / total input ) * 100%

= (210/42000) * 100%

= 5%