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Home electricity lab: energy, the bill and safety

Why is the electricity bill high this month? Choose the appliances in a home, calculate the energy and the cost, and learn to use electricity safely.

42.5 kWhkWh × priceI = P ÷ Vfuse 13 A
LevelS2 to S5 (and IGCSE)
TimeAbout 35 min
You usePower, kWh, tariffs, current
PriceFree: no account

🎯 Aim

To calculate the energy used by household appliances, the monthly bill with block tariffs, and the current and fuse needed for safety.

You will learn to

  • Calculate energy in kWh from power and time.
  • Calculate a bill with block tariffs.
  • Calculate current with I = P ÷ V and choose a fuse.
  • Explain electrical safety rules.

🧭 What to do

  1. Set the number of each appliance and the hours it is used each day.
  2. Read the energy per month and the bill.
  3. Find the appliance that uses the most energy on the bar chart.
  4. Choose a Fuse or circuit breaker and add a kettle and an iron: does the fuse hold?
  5. Answer the questions with the class data.
  6. Write your conclusion and download your lab report.

🔬 Lab bench

📋 The data

Appliances, power and hours of use in one family’s home.

🧠 Investigate: answer from the data

Type your answer and tap Check. Use 💡 Hint first; open the method only when you are stuck.

📄 My lab report

Your report collects the aim, your data table, the graphs, your answers and your conclusion. It is made on your phone or computer: nothing is sent to anyone.

Check your conclusion

Energy = power × time, so a fridge of 60 W running all day uses more energy than a 1 000 W iron used for half an hour. The bill rises quickly above 50 kWh a month because of the block tariff. High-power appliances take a large current (I = P ÷ V), so a fuse or breaker protects the cables; it must never be bypassed.

➕ Get more from this experiment

📝 Free

Print the worksheet (button above), download the data, and save your report. Teachers can project this page in class.

📦 Premium Lab Pack

1 000 RWF

  • Home energy survey worksheet for learners’ own homes
  • Electrical safety checklist and bill calculations
  • Teacher guide and answer key
  • Exam-style questions with marking scheme

👩‍🏫 For teachers

Use it as a practical when apparatus is missing, as homework, or as a project. Free lesson plans help you plan, teach and assess.

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DONAT STEM Interactive Labs · original work by BIZIYAREMYE Donat · data are realistic models for learning · free forever