NEB Physics: How to Crack Short Conceptual Questions | Class 11 & 12
Crack the short questions
Seven exam-day strategies — with real examples from Physics — that separate full-marks answers from half-marks ones.
Core strategies
Don't panic
Most students freeze the moment they read the question. That's normal — and it passes. Just calmly remember the concepts you've studied so far.
Physics rule of thumb
Panic time ∝ 1 / Preparation. The more you've practiced, the quieter that first-glance fear gets.
Read the question carefully — twice
Short questions are built on precise language. Underline key words before writing anything. The difference between "can" and "must", or "speed" and "velocity", is often the entire answer.
Classic NEB question
"Can a body have constant speed but varying velocity?"
Yes — because velocity is a vector. Circular motion: |v| is constant, but direction keeps changing, so velocity varies.
Back every claim with a formula
Logic alone earns partial marks. Equations earn full marks. Examiners look for mathematical support — even one relevant formula signals that you understand the physics, not just the words.
Without formula
"Velocity changes direction in circular motion."
With formula ✓
"Centripetal acceleration a = v²/r acts inward, continuously changing the direction of v = rω."
Draw a diagram when in doubt
A neat, labelled diagram can replace two sentences of confused explanation — and it shows the examiner you can visualise the problem. You don't need artistic skill; you need correct labels and arrows.
When to draw
Ray optics (reflection/refraction), projectile paths, free-body diagrams, electric field lines, wave superposition — always sketch these first.
Define terms before using them
If the question uses a term — or if your answer hinges on one — define it first. This proves conceptual clarity and protects you from losing marks on ambiguity.
Example pattern
"Surface tension (T) is the force per unit length acting tangentially at the surface of a liquid…" — then proceed to answer with T = F/L.
Use dimensional analysis to self-check
Before writing a final formula, verify its dimensions. Dimensions don't lie — if both sides of an equation don't match, something is wrong. This habit alone can save marks on derivation questions.
Quick check
Checking F = ma: [kg·m/s²] = [kg][m/s²] ✓
If you wrote F = mv, dimensions give [kg·m/s] ≠ [kg·m/s²] — caught!
Attempt every question — never leave a blank
A blank guarantees zero. A partial attempt — even just a correct definition or a relevant formula — can earn 1 or 2 marks. NEB examiners give credit for anything that shows understanding.
Strategy for unknowns
Write what the question reminds you of → state the relevant law or principle → write its formula → apply what you can. Even step 1 alone can get partial credit.
Worked examples — strategies in action
Two real NEB-style questions solved step by step, with each strategy called out as it's used.
Question 1 · Mechanics
"Why does a cyclist lean inward while taking a turn?"
Don't panic — identify the concept
The question is about a cyclist turning. This reminds you of circular motion and centripetal force. Good — you have a foothold.
Read carefully — what's really being asked?
The keyword is "why" — the examiner wants a cause, not just a description. You must explain the force balance that requires leaning.
Define the terms first
Start with: "When a body moves in a circular path, a centripetal force directed toward the centre is required."
Back it with a formula
When the cyclist leans at angle θ, the normal reaction N and weight mg give:
Draw a diagram
Model answer
When a cyclist takes a turn, centripetal force (F_c = mv²/r) directed toward the centre is required. By leaning inward at angle θ, the horizontal component of the normal reaction N provides this force, while the vertical component balances weight mg. The lean angle satisfies tan θ = v²/rg. Without leaning, there would be no horizontal force, and the cyclist would skid outward.
Question 2 · Modern Physics
"Can a photon and an electron have the same wavelength? Explain."
Don't panic — two concepts, not one
The question involves a photon (light) and an electron (matter). This points to wave-particle duality and de Broglie's hypothesis.
Read carefully — the word "can"
"Can" asks whether it is possible — not whether it always happens. The answer is Yes, and you must show the condition under which it holds.
Define, then compare
Photon wavelength: λ = hc/E. Electron wavelength: λ = h/mv. Both are wavelengths — so they can be equal for particular values of E and mv.
Back it with formulas
Electron: λ = h / mv
Equal when: E = mvc
Dimension check
Model answer
Yes. A photon's wavelength is given by λ = hc/E, while an electron's de Broglie wavelength is λ = h/mv. For equal wavelengths: hc/E = h/mv, giving E = mvc. Thus a photon of energy mvc and an electron moving at speed v will have identical wavelengths, even though one is radiation and the other is a particle.
Quick reference — common short-question formulas
| Formula | Quantity | Where it appears |
|---|---|---|
| v = u + at | Velocity (kinematic) | Equations of motion |
| a = v²/r | Centripetal acceleration | Circular motion |
| PV = nRT | Ideal gas state | Kinetic theory |
| λ = h/mv | de Broglie wavelength | Modern physics |
| T = F/l | Surface tension | Properties of matter |
| E = hf | Photon energy | Photoelectric effect |
| n = sin i / sin r | Refractive index (Snell) | Geometrical optics |
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