Electrical power and energy
Watts, kilowatt-hours and what it costs to run a fridge, a fan or a computer.
Planned. This module is part of the plan and is not written yet.
Why it matters
A clinic's vaccine fridge runs day and night. Its watts and hours tell you how much energy it needs, and so how much solar power has to be set aside for it.
Draft outline · in review- For
- Level 9–10 · JSS 3 (BECE) to SSS 1
- Inside
- 5 lessons and a test · about 75 minutes
- Topic
- Electricity · core, 2 of 4
Inside the module.
5 lessons in order, about 75 minutes in all, then a short test. Learners go at their own pace; the minutes are a guide, not a timetable.
Draft outline · in review
Lesson 1: Power: P = V × I
Power is the rate of using energy, in watts.
Explain15 min, from minute 0
Lesson 2: Watts from volts and amps
Find the power of a fan, a bulb and a laptop charger.
Worked example15 min, from minute 15
Lesson 3: Watt-hours and kilowatt-hours
Energy = power × time, and why 1 kWh = 1,000 Wh.
Explain15 min, from minute 30
Lesson 4: A day of appliances
Work out a household's daily energy from a list of appliances.
Practice20 min, from minute 45
Lesson 5: Check your skills
Mixed power and energy problems.
Review10 min, from minute 65
End-of-module test
Calculate power with P = V × I, and energy in watt-hours and kilowatt-hours, including an appliance's daily use.
Mastered at 85% or more. Retake it until you pass; nothing is lost, and each try gives feedback.
Already know it? A Challenge Test (planned) clears the whole module: 90% overall, no objective below 75%.
Last stageafter about 75 min
Practicalities
Draft outline · in reviewBuilt to run offline
Planned to run on the Lantern's own computer, with no internet needed.
Languages
Planned first in English; every module aims to reach all of the Lantern's languages.
Try a question.
One question from the module, as a learner would meet it. Have a go, then open the worked solution a step at a time.
Draft outline · in review
A fan runs on 230 V and draws 0.25 A. It runs for 8 hours a day. What is its power, and how much energy does it use in a day, in kWh?
Work it out on paper first, then show the answer and mark it yourself.
Particulars
Where it sits
What a learner can do after it
- Use P = V × I to calculate power in watts.
- Calculate energy in watt-hours and kilowatt-hours from power and time.
- Work out the energy an appliance uses in a day.
Needs first
We suggest first (never a lock)
Level
Level 9–10 · JSS 3 (BECE) to SSS 1
Level mappings are approximate. A qualified teacher or lecturer in each country must check them before they appear in the app.
Difficulty for its level
2 of 4 · Core
Time
About 75 minutes
Alignments
- Aligned to WASSCEpartial · in reviewWASSCE Physics syllabus: electrical energy and power
- Aligned to GCSEpartial · in reviewGCSE Physics: energy transfers and power in circuits (descriptive ref)
Alignment in review until a qualified teacher or lecturer checks it. No exam body, university or vendor endorses us; learners still sit the real exam.
Challenge Test
Planned: a Challenge Test to prove you know it and skip it. Pass at 90% overall, with no objective below 75%.
University courses it previews
Physics, Electrical Engineering, Mechanical Engineering, Medicine and Surgery
On these pathways
The route here.
Everything this module builds on, drawn as a route from its foundations. Solid lanes must be mastered first, or cleared by a Challenge Test; dashed lanes are suggestions that never lock anything.
- MA-ALG-FRM-01Substituting into formulaeMaths · JSS 1 to JSS 2 (Level 7–8) · Planned · recommended
- SC-PHY-ELC-01Circuits and currentSciences · JSS 1 to JSS 2 (Level 7–8) · Planned
- SC-PHY-ELC-02Voltage, current and resistanceSciences · JSS 2 to JSS 3 (BECE) (Level 8–9) · Planned Needs Circuits and current (required), Substituting into formulae (recommended).
- SC-PHY-ELC-03Electrical power and energySciences · JSS 3 (BECE) to SSS 1 (Level 9–10) · Planned · the destination Needs Voltage, current and resistance (required), Substituting into formulae (recommended).
Help light the room where this is learned.
Every route on this map starts in a classroom with 24 stations, a tutor that works offline and a facilitator upstairs. Four are planned and waiting for light.