Question

What is the energy efficiency of a light bulb that gives you 30 units of usable energy for every 100 units of energy put in to it?
a. 0.3
b. 3
c. 30

Answer 1

Answer:

Explanation:

Given parameters:

Energy output = 30units

Energy input = 100units

problem:

Energy efficiency of light bulb:

Solution:

 Efficiency is given as:

    Efficieny = \frac{energy_{output} }{energy_{input } x100

   Efficieny = $\frac{30}{100}$ x 100 = 30%

 

Answer 2

Answer:

The correct answer is option a.

Explanation:

Efficiency is defined as the ratio of output energy to input energy.

Efficiency(e)=$\frac{E_o}{E_i}$

Energy given out by the system = $E_o$

Energy given to the system = $E_i$

Here we are given with : $E_o-30 units,E_i=100$

Efficiency of of a light bulb:

$e=\frac{30 units}{100 units}=0.3$