IB MYP Integrated Sciences e-Assessment : Power and efficiency Exam Style Practice Questions - New Syllabus
Question (2 marks)
Incandescent light bulbs and light-emitting diode (LED) light bulbs are two types of light bulb.
These bulbs have different efficiencies. A comparison of the two bulbs is shown below.
Efficiency can be calculated using the following formula:
Calculate the efficiency of each light bulb.
Efficiency of incandescent light bulb
Efficiency of LED light bulb
▶️Answer/Explanation
Ans:
Efficiency of Incandescent Light Bulb
Useful light energy output = \( 10 \, \text{J} \)
Total electrical energy input = \( 100 \, \text{J} \)
$
\text{Efficiency} = \left( \frac{10}{100} \right) \times 100 = 10\%
$
Efficiency of LED Light Bulb
Useful light energy output = \( 75 \, \text{J} \)
Total electrical energy input = \( 100 \, \text{J} \)
$
\text{Efficiency} = \left( \frac{75}{100} \right) \times 100 = 75\%
$