Physics: Concepts, Signs and One-Step Numericals
Physics carries 35 questions and tests conceptual understanding plus numerical fluency across mechanics, electricity and magnetism, optics, heat, waves, and modern physics. The paper favours one- or two-step calculations, so formula recall and unit discipline matter as much as theory.
Mechanics and properties of matter
Revise kinematics, Newton's laws, work-energy, rotational motion, gravitation, simple harmonic motion, and elasticity. Watch vector directions and the choice of sign convention.
Electricity, magnetism and optics
Current electricity, capacitors, magnetic effects, electromagnetic induction, alternating current, ray optics, and wave optics dominate. Know series and parallel combinations, Kirchhoff's rules, and lens/mirror formulas with signs.
Modern physics
Photoelectric effect, atomic models, nuclear reactions, and semiconductors. Conservation of energy and of charge and mass number solves most items.
Worked example
A convex lens of focal length 10 cm forms a real image twice the object's size. Find the object distance. For a real inverted image, magnification magnitude is 2, so v = 2u. Using 1/f = 1/v + 1/u with u positive: 1/10 = 1/(2u) + 1/u = 3/(2u), so 2u = 30 and u = 15 cm.
Traps
- Mixing sign conventions between mirror and lens formulas.
- Using peak instead of rms values in AC power calculations.
- Forgetting internal resistance when computing terminal voltage.
- Treating g as constant over large heights or ignoring air resistance unless told to.