Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Question
(a) What happens to the saturation current when intensity is doubled at the same frequency? (1 mark)
(b) What happens to the stopping potential when intensity is doubled at the same frequency? (1 mark)
(c) What happens to the stopping potential when frequency is increased above threshold? (1 mark)
(d) Give the physical reason for your answer in part (c). (1 mark)