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Case-based questions look long and unfamiliar, which is why students fear them. A paragraph about wearable electronics or a household geyser, then four parts, some multiple choice and some written. But the physics inside is the same physics as the rest of the paper. This post explains what CBSE means by competency-based questions, how to answer them and how to practise.
What does CBSE mean by competency-based questions?
CBSE's competency-based education site describes the approach as focusing on whether students can demonstrate learning outcomes, and says its assessments apply knowledge and skills to real-world contexts using authentic problems that draw on real-life data. The board's 2026-27 senior secondary curriculum document asks schools to assess competencies through methods such as case-based questions.
In practice, a competency-based question gives you a situation and asks you to decide which idea applies. That is the hard part. The calculation that follows is usually routine.
What do these questions look like in the board paper?
The CBSE Class 12 Physics sample paper for 2026-27 shows the format. Section A has 16 one-mark questions, of which four are assertion-reason items. Section D has two case-study questions of four marks each, and each case is a short passage followed by four one-mark parts. In the sample paper, one case is about flexible polymer semiconductors and the other about Einstein's explanation of the photoelectric effect.
The Physics curriculum for 2026-27 puts about 38% of theory marks on remembering and understanding, about 32% on applying, and about 30% on analysing, evaluating and creating. Check your own year's sample paper, since CBSE publishes a new one each session.
How do you answer a case-based question?
Read the parts before the passage. Knowing what you are looking for makes the passage shorter.
Name the chapter and the law. Write it in the margin: "electric power, P = VI = V²/R".
Pull out the numbers with units. List them before you calculate.
Answer each part on its own. One part usually does not depend on the others. If you are stuck on part II, part III may still be easy.
Use physics, not just the passage. The passage gives context; the marks are for the physics reason.
Worked example: a case about a geyser
*A family installs a 2000 W, 220 V geyser. They use it for 30 minutes every morning. Electricity costs ₹8 per unit (1 unit = 1 kWh).*
I. What current does the geyser draw? I = P/V = 2000/220 ≈ 9.1 A.
II. What is its resistance when working? R = V²/P = 220² / 2000 = 48,400 / 2000 = 24.2 Ω.
III. What does one morning's use cost? Energy = 2 kW × 0.5 h = 1 kWh = 1 unit, so the cost is ₹8.
IV. Would a 5 A fuse be suitable for this circuit? Give a reason. No. The geyser draws about 9.1 A, more than 5 A, so the fuse would melt as soon as the geyser was switched on.
The mistakes to avoid: leaving power in watts and time in minutes when calculating units, and answering part IV with "no" but no reason.
How do assertion-reason questions work?
You get two statements. Decide whether each is true, and then whether the reason explains the assertion.
*Assertion: Two identical heaters connected in parallel to a supply consume more power than the same heaters connected in series. Reason: In parallel, each heater gets the full supply voltage.*
Check with numbers. Each heater has power P at full voltage. In series, each gets half the voltage, so each uses P/4 and the pair uses P/2. In parallel, each uses P, so the pair uses 2P. Both statements are true, and the reason explains the assertion. Working a quick example, rather than trusting how the sentences sound, is the reliable way through these.
How should you practise for them?
Competency questions test transfer: using what you learned in a new setting. In experiments by Butler (2010), students who repeatedly tested themselves on prose passages did better a week later than students who repeatedly restudied, both on the same questions and on new inferential questions, including questions from a different knowledge domain.
Retrieve, don't reread. After each chapter, answer five questions without notes.
Write your own case. Take a household device, a news item or a sports scene and write four questions about it. Our guide on writing your own questions shows how.
Mix chapters. Each week, do one set of cases from three different chapters, so you practise picking the idea.
Use CBSE's own questions. The board posts additional practice questions with marking schemes for Class 12 subjects.
When you know the chapter but cannot see how it applies to the situation, work through a few fully explained solutions. The Fermi Problem Library has a step-by-step solver that explains the reasoning rather than printing an answer. To fit this into your board revision, see our 8-week Class 12 revision plan.
This week, pick one appliance at home and write a four-part case question about it, then solve it.
