x̄ - > KCSE Physics Topical Question Bank (1996–2024)

Organised by topic — each card contains a concept focus, a sampled KCSE question (1996–2024), a worked solution and marking tips. Ideal for focused revision and classroom practice.

1. Mechanics — Motion & Kinematics

Concept focus: displacement, velocity, speed, acceleration, SUVAT equations, graphs of motion.

Sample KCSE 2014 – Paper 1
A car accelerates uniformly from rest to 20 m s⁻¹ in 10 s. Find its acceleration and the distance covered.

Acceleration a = (v − u)/t = (20 − 0)/10 = 2.0 m s⁻². Distance s = ut + ½at² = 0 + 0.5×2×10² = 100 m.

✅ Marking tip: 1 mark for a, 1 mark for s, 1 mark for correct units (3 marks).

2. Forces & Dynamics

Concept focus: Newton's laws, friction, equilibrium, free-body diagrams, terminal velocity.

Sample KCSE 2016 – Paper 2
A block of mass 5 kg is acted upon by a horizontal force of 30 N. If frictional force is 10 N, find the acceleration.

Net force = 30 − 10 = 20 N. a = F/m = 20/5 = 4.0 m s⁻².

✅ Marking tip: 1 mark net force, 1 mark for division, 1 mark units.

3. Work, Energy & Power

Concept focus: kinetic/potential energy, work done, power, conservation of energy, efficiency.

Sample KCSE 2015 – Paper 1
A 2 kg mass is raised 5 m vertically. Find the gravitational potential energy gained (g=9.8 m s⁻²).

ΔPE = mgh = 2×9.8×5 = 98 J.

✅ Marking tip: 1 mark for substitution, 1 mark for final value and units.

4. Momentum & Collisions

Concept focus: linear momentum, impulse, conservation of momentum, elastic and inelastic collisions.

Sample KCSE 2012 – Paper 2
Two gliders of masses 0.4 kg and 0.6 kg move towards each other with speeds 2 m s⁻¹ and 1 m s⁻¹ respectively. They collide and stick together. Find their common velocity.

Take + to right. Initial momentum = 0.4×2 + 0.6×(−1) = 0.8 − 0.6 = 0.2 kg m s⁻¹. Total mass = 1.0 kg. v = 0.2/1.0 = 0.2 m s⁻¹ (to the right).

✅ Marking tip: 1 mark sign convention, 1 mark momentum calc, 1 mark division and direction.

5. Waves — Sound & Light

Concept focus: wave properties, speed = frequency × wavelength, reflection, refraction, Snell's law, wavefronts.

Sample KCSE 2018 – Paper 1
A wave has frequency 500 Hz and wavelength 0.68 m. Find its speed.

v = fλ = 500 × 0.68 = 340 m s⁻¹.

✅ Marking tip: 1 mark formula, 1 mark substitution, 1 mark answer & units.

6. Electricity & Magnetism

Concept focus: current, voltage, resistance (Ohm's law), series & parallel circuits, magnetic fields, electromagnetic induction.

Sample KCSE 2017 – Paper 2
Two resistors 6 Ω and 3 Ω are connected in parallel to a 12 V battery. Find the current drawn from the battery.

Equivalent resistance R = 1/(1/6 + 1/3) = 1/(1/6 + 2/6) = 1/(3/6) = 2 Ω. I = V/R = 12/2 = 6 A.

✅ Marking tip: 1 mark correct parallel formula, 1 mark R, 1 mark I & units.

7. Thermal Physics

Concept focus: temperature scales, heat capacity, specific heat capacity, latent heat, thermal expansion.

Sample KCSE 2013 – Paper 1
How much energy is required to raise 0.5 kg of water from 20°C to 80°C? (Specific heat capacity of water = 4200 J kg⁻¹ K⁻¹)

Q = mcΔT = 0.5×4200×(80−20) = 0.5×4200×60 = 126,000 J.

✅ Marking tip: 1 mark formula, 1 mark substitution, 1 mark final.

8. Optics

Concept focus: reflection, refraction, lenses (thin lens equation), image formation, magnification, total internal reflection.

Sample KCSE 2016 – Paper 1
An object is placed 15 cm from a converging lens of focal length 10 cm. Find the image distance and nature of the image.

Using lens formula 1/v + 1/u = 1/f ⇒ 1/v = 1/f − 1/u = 1/10 − 1/15 = (3−2)/30 = 1/30 ⇒ v = 30 cm. Image is real, inverted and magnified (m = v/u = 30/15 = 2).

✅ Marking tip: 1 mark rearranging lens formula, 1 mark v, 1 mark image nature and magnification.

9. Modern Physics — Radioactivity & Atomic Models

Concept focus: α, β, γ radiation, half-life, safety, simple nuclear reactions and atomic models.

Sample KCSE 2011 – Paper 2
The half-life of a radioactive substance is 3 hours. What fraction remains after 9 hours?

After 9 hours (3 half-lives): fraction = (1/2)³ = 1/8.

✅ Marking tip: 1 mark recognition of 3 half-lives, 1 mark final fraction.

10. Properties of Matter — Density & Pressure

Concept focus: density, pressure in fluids, upthrust, Pascal's principle, Hooke's law (elasticity).

Sample KCSE 2019 – Paper 1
Find the density of a cube of mass 250 g and side 5 cm.

Volume = 5³ = 125 cm³ = 1.25×10⁻⁴ m³ (if SI). Density = mass/volume = 0.25 kg / 1.25×10⁻⁴ m³ = 2000 kg m⁻³. If using g/cm³: 250/125 = 2.0 g cm⁻³.

✅ Marking tip: 1 mark for volume, 1 mark for density calc, 1 mark units.

11. Practical Skills & Experimental Techniques

Concept focus: measurements, uncertainties, reading instruments, plotting graphs, interpreting slopes and intercepts.

Sample KCSE 2018 – Paper 2
In an experiment to determine g using a simple pendulum, the period T for various lengths L is measured. State a graph to plot and how g is obtained from slope.

Plot T² (y-axis) against L (x-axis); for a simple pendulum T² = (4π²/g) L. Slope = 4π²/g ⇒ g = 4π² / slope.

✅ Marking tip: 1 mark for choosing T² vs L, 1 mark for relation of slope to g.

12. Electronics & Instrumentation

Concept focus: diodes, transistors (basic), logic gates (conceptual), signal measurement, oscilloscopes basics.

Sample KCSE 2010 – Paper 2
State the function of a diode in a circuit.

A diode allows current to flow in one direction only (rectification); it blocks current in reverse bias.

✅ Marking tip: 1–2 marks for correct function and brief explanation.

KCSE Physics Topical Question Bank (1996–2024) — focused revision cards: concise concept notes, KCSE past-paper style practice, worked answers and examiner hints. If you want this exported as a downloadable HTML file or printable PDF, I can prepare it.