Electrical Energy and Power: JAMB Physics Questions, Answers & Notes

What Electrical Energy and Power covers in the JAMB Physics syllabus

Electrical power P = IV, which can also be written P = I²R or V²/R (unit: watt). Electrical energy E = Pt (joules), but bills use the kilowatt-hour (kWh) — power in kW × time in hours; cost = units × price per unit. Current draws follow I = P/V. The heating effect (I²R) powers kettles, heaters and lamps, and a fuse protects a circuit by melting when the current is too high (rate it just above the operating current). Power is transmitted at high voltage to keep the current — and thus the I²R losses in the cables — low.

For Electrical Energy and Power, JAMB expects you to be able to:

• Apply P = IV, I²R and V²/R to calculate power
• Calculate electrical energy in joules and kilowatt-hours and its cost
• Explain the heating effect, fuses and high-voltage transmission

Key facts & revision notes: Electrical Energy and Power

These are the recurring points our Electrical Energy and Power questions test — revise them until each feels automatic, then practise the questions above to lock them in.

• Electrical power P = IV (current × voltage).
• Power is measured in watts (W).
• P = IV = 0.5 × 240 = 120 W.
• Electrical energy E = power × time = Pt.
• Electrical energy is measured in joules (J).
• Electricity is billed in kilowatt-hours (kWh), the 'unit' of electrical energy.
• P = I²R = 3² × 4 = 9 × 4 = 36 W.
• Energy = power (kW) × time (h) = 1 kW × 2 h = 2 kWh.
• P = V²/R = 240²/120 = 57600/120 = 480 W.
• A fuse melts and breaks the circuit when excessive current flows, protecting appliances.
• Electric kettles, heaters and irons use the heating effect of current (I²R heating).
• Energy = 2 kW × 3 h = 6 kWh; cost = 6 × ₦50 = ₦300.
• t = 5 × 3600 = 18000 s; E = 60 × 18000 = 1080000 J.
• At the same voltage, P = IV means higher power needs a larger current.
• A power of 1500 W means 1500 joules of energy are used each second.
• High voltage means lower current for the same power, reducing I²R heat loss in transmission lines.
• I = P/V = 2200/220 = 10 A.
• Valid forms are IV, I²R and V²/R.
• 'IR²' is not a power formula.
• Operating current = P/V = 960/240 = 4 A, so the fuse rating should be just above 4 A.
• A filament lamp converts electrical energy into heat and light.
• P = VI = 240 × 0.25 = 60 W.
• E = Pt = 100 × 60 = 6000 J.
• P = V²/R = 220²/110 = 48 400/110 = 440 W.

Worked examples

Three Electrical Energy and Power questions with the answer and a short explanation, so you can see how the topic is set before you practise the full set.

How Electrical Energy and Power is tested in JAMB Physics

Our Electrical Energy and Power bank holds 40 questions (6 easy, 22 medium, 12 hard). JAMB Physics typically returns to Electrical Energy and Power year after year, so steady practice on this topic is high-value revision. Questions are multiple-choice with four options, and at UTME pace you get roughly 40 seconds each — which is why timed practice matters.

How to answer Electrical Energy and Power questions

Work the stem first and predict the answer before you look at the options; then eliminate the ones that contradict the key facts above. Watch for “which is not…”, “all of the above” and “except” style stems, which are where rushed candidates lose easy marks on Electrical Energy and Power. If a calculation or a precise definition is involved, work it from first principles rather than guessing from a half-remembered rule. When two options look right, re-read the stem for the qualifier that separates them — JAMB rarely repeats an option by accident. If you are still unsure, eliminate the two weakest choices to lift your odds, flag the question, and move on; never burn a full minute on one Physics item when the exam gives you about forty seconds each. Then come back to flagged questions with whatever time remains. The single most reliable way to get faster at Electrical Energy and Power is repeated timed practice, so use the button above until the recurring patterns feel automatic.

Common mistakes to avoid in Electrical Energy and Power

The errors that cost marks on Electrical Energy and Power are usually careless rather than conceptual: misreading a negative stem, confusing two similar terms, or rushing a definition you actually know. Candidates also over-rely on “expo” and last-minute cramming instead of understanding the topic — which fails the moment JAMB rephrases a familiar idea. Treat every option as a claim to be checked against the facts above, keep your working tidy for any calculation, and don’t change a considered answer on a hunch. Above all, revise Electrical Energy and Power actively by answering questions, not just by re-reading notes — recall under time is what the exam rewards.

Frequently asked questions

Is Electrical Energy and Power part of the JAMB Physics syllabus?

Yes. Electrical Energy and Power is a recognised topic in the JAMB Physics syllabus, covering apply P = IV, I²R and V²/R to calculate power. You should be able to recall its key facts and apply them to multiple-choice questions.

How many Electrical Energy and Power questions can I practise on Belmadeng?

There are 40 original, JAMB-standard Electrical Energy and Power questions in our free bank, each with the correct answer and a worked explanation. You can practise them untimed or as a timed test.

What are the most important points to know about Electrical Energy and Power?

Electrical power P = IV, which can also be written P = I²R or V²/R (unit: watt). Electrical energy E = Pt (joules), but bills use the kilowatt-hour (kWh) — power in kW × time in hours; cost = units × price per unit. Current draws follow I = P/V. The heating effect (I²R) powers kettles, heaters and l…

How do I answer Electrical Energy and Power questions quickly in JAMB?

Read the stem carefully, eliminate clearly wrong options, and match the remaining choices to the key facts for Electrical Energy and Power. Practising timed Electrical Energy and Power questions builds the speed you need for UTME's pace of about 40 seconds per question.

Are these JAMB Physics Electrical Energy and Power questions past questions or original?

They are original questions written to JAMB (UTME) standard and mapped to the official syllabus — not reproduced past papers. This keeps them legal to use freely while closely mirroring how the real exam tests the topic.

Where can I practise Electrical Energy and Power questions free without signing up?

Right here — tap “Start Electrical Energy and Power practice” on this page to begin instantly. Belmadeng's CBT practice is completely free and needs no sign-up, download or subscription.

About these questions: original, JAMB-standard items written from the official UTME Physics syllabus (last reviewed 2026-09-18). Belmadeng is an independent study platform and is not affiliated with JAMB. Spotted an error? Use the report link.