Page 21 - Q & A STPM 2022 Physics

Chapter
14 Electric Current

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14.1 Conduction of Electricity

Section A Multiple-choice Questions

Question 1
An electrical fan rotates when the equipment is switched on. What are the charge
carriers that convey the current in the fan?
A Electrons only
B Negative ions only
C Holes and electrons
D Lattice atoms and free electrons

Answer: A
The charge carriers in a metal conductor are purely free electrons.

Semester
2 Question 2
When a conductor carries a current, the number of conduction electrons that
flow in the conductor for 10 s is 3.75 × 10 . What is the current that flows in
20
the conductor?
A 3.8 A C 6.0 A
B 4.2 A D 10 A

Answer: C Exam Tips
Exam Tips
Q
I =
t Electric current is defined
as the rate of flow of charge
= Ne in the circuit in a definite
t direction.
–19
20
(3.75 × 10 )(1.6 × 10 ) dQ
= I =
10 dt
= 6.0 A

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014 STPM Q&A Physics T2.indd 220 17/02/2022 10:12 AM