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

The correct answer is option a.

Step-by-step explanation:

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

Efficiency(e)=
`(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=(30 units)/(100 units)=0.3`

Answer 2

Step-by-step 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 =
`(30)/(100)` x 100 = 30%