WASSCE Physics · Paper 1 style

Modern physics

One sample question with the full working. 5 more in the app, with instant feedback and repair sessions for the traps below.

An n-type semiconductor is produced by doping silicon with

Apure silicon only
Ba pentavalent (group V) element such as phosphorus
Ca trivalent element such as boron
Da noble gas

Show the answer and working

Answer: B

Provides extra free electrons.

Trap A Takes part of the condition as the whole answer: Check whether the option is enough on its own. Equilibrium needs zero resultant force AND zero total moment; a complete explanation names every factor in the stem.

Trap C Mixes up a pair of similar physics terms: Make a two-column table for each pair with one defining feature and an example. Underline the defining word in the stem before you look at the options.

Trap D Uses everyday intuition instead of physics: Name the law that applies (Newton's first law, Archimedes' principle, kinetic theory) and reason from it. If the option only 'feels' right, test it against the law.

Traps in Modern physics

Takes part of the condition as the whole answer
Check whether the option is enough on its own. Equilibrium needs zero resultant force AND zero total moment; a complete explanation names every factor in the stem.
Mixes up a pair of similar physics terms
Make a two-column table for each pair with one defining feature and an example. Underline the defining word in the stem before you look at the options.
Uses everyday intuition instead of physics
Name the law that applies (Newton's first law, Archimedes' principle, kinetic theory) and reason from it. If the option only 'feels' right, test it against the law.
Chooses a true but irrelevant statement
Re-read the question word (why, which, what causes). A true fact that answers a different question is still wrong.
Reverses a relationship or direction
Write the relationship with an arrow or proportionality sign first (E ∝ f; R ∝ L; cooling a metal → R falls). Then check the option follows the same direction.
Picks a related law, device or effect with a different job
Learn laws and devices as 'name → what it tells you' cards. Contrast neighbours: left-hand rule = motor force, right-hand rule = dynamo current, grip rule = field around a wire.
Field and charge misconceptions
Like charges/poles repel, unlike attract. Field lines go from N to S (magnetic) and + to − (electric). Fleming's LEFT hand: motors (force); RIGHT hand: generators (induced current).

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