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Household Energy Exploration

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Household Energy Exploration

Investigate how electrical energy is used and transformed in a household. Read the self-contained home energy log, then solve the challenges. Show working for calculations. Energy used = power (kW) × time (h). Electricity cost = energy (kWh) × price per kWh.

The energy log

A household checks the labels and meter readings for one day. The fridge runs for a total of 10 hours at 120 W. A television uses 5 W in standby for 20 hours. A kettle rated at 2,000 W runs for 6 minutes. The electricity price is $0.30 per kWh. Remember: 1 kW = 1,000 W, and 1 hour = 60 minutes.

Investigate and calculate

Use the energy log and your understanding of energy transfers to complete each challenge.

1.Which appliance in the energy log is designed to operate regularly throughout the day to keep food cold?

The fridge
The kettle
The television
A ceiling light

2.The television is switched off but remains in standby. What does this situation illustrate, and what is one way to reduce the wasted energy?

3.Calculate the fridge’s electrical energy use during its 10 hours of operation. Give your answer in kWh. Show the conversion and calculation.

4.How much energy does the television use in standby over 20 hours? Give your answer in kWh. Show your working.

5.The kettle runs for 6 minutes. Calculate its energy use in kWh. Show how you convert minutes to hours.

6.Match each appliance to its main useful energy output while operating. An output can be used more than once: A. kettle; B. ceiling light; C. washing machine drum; D. television screen.

A. Kettle
B. Ceiling light
C. Washing machine drum
D. Television screen

Light energy
Thermal (heat) energy
Kinetic (movement) energy
Light energy

7.A household uses 1.2 kWh each day to run its fridge. At $0.30 per kWh, calculate the fridge’s electricity cost for 7 days. Show your working and give the answer in dollars.

8.A student says, “The kettle uses more energy than the fridge because its power rating is much higher.” Use the energy log to explain why power rating alone is not enough to compare energy use.

9.True or false? In an appliance, energy can be transferred or transformed into other forms, but it is not created or destroyed. Give one example from the home energy log to support your choice.

TrueFalse

10.Recommend one realistic change the household could make to reduce unnecessary electricity use. Explain the energy-saving idea behind your suggestion.