Page 58 - Focus TG4 KSSM (Physics) Terbitan Penerbitan Pelangi Sdn Bhd

Physics Form 4 Answers

Since the speed of sound waves (ii) Q3 v = s , therefore,
is higher at higher temperature of t
air, refraction occurs and the sound a t = s
waves are refracted towards the v
surface of the Earth. This results in = 320 000 × 1000
8
the listener be able to hear clearer a 3 × 10
sound at night. = 1.07 s
Checkpoint 5.5 Q2 (a) • A: An up-and-down movement Q4 P : Microwaves; Q : X-rays; R :
with a large amplitude Visible light; S : Ultraviolet rays
Q1 (a) • B: No motion/stationary
(b) a = 3.0 cm; D = 30.0 cm; SPM Practice 5
x = 15.0 cm
ax Objective Questions
λ =
D 1. D 2. B 3. D 4. C 5. C
3.0 × 15.0 6. B 7. C 8. D 9. B 10. B
= 30.0
(b) = 1.5 cm 11. A 12. C 13. C 14. C 15. B
16. D 17. A 18. B 19. A 20. C
–9
Q3 (a) λ = 540 nm = 540 × 10 m 21. B 22. D 23. A 24. D 25. C
–3
a = 0.4 mm = 0.4 × 10 m 26. D 27. D
D = 3.0 m
Using λ = ax , Subjective Questions
D
(c) λD 540 × 10 × 3.0
–9
x = a = 0.4 × 10 –3 Section A
= 4.05 × 10 m 1. (a)
–3
= 4.1 mm Direction of
λD movement of hand
(b) • x = a
Q2 (a) Remains unchanged • Hence, if λ is bigger, x will
(b) Remains unchanged also be bigger. Therefore, (Accept single arrow)
(c) Remains unchanged the distance between two
adjacent bright fringes of light
Q3 (a) will be bigger. (b) λ = v
f
Q4 (a) f = 600 Hz; v = 330 m s –1 = 0.90
Using v = fλ, 3.0
v 330
λ = — = —— = 0.3 m
f 600 (c)
(b) The leaves which act as = 0.55 m
obstacles have small width. (b) a = 1.5 m; D = 3.0 m;
Therefore, the effect of x = λD
diffraction is greater. Hence the a
waves join back after a short = 0.55 × 3.0
distance from the leaves. 1.5
(c) The log which is a larger = 1.1 m
obstacle causes less diffraction.
The waves join back after a Checkpoint 5.7 2. (a) Diffraction of waves
futher distance from the log. Q1 1. They all transfer energy from (b) • The amplitude of the waves
Q4 (a) The sound waves spread out one place to another. before passing through the
beyond the edge of the window 2. They are all transverse waves. slit is higher than that the
after passing through the 3. They can all travel through a amplitude after passing
window. vacuum. through the slit.
(b) Diffraction of sound waves 4. They all travel with a speed of • This is because the waves
3 × 10 m s in vacuum. spread over a larger area and
8
–1
energy per unit area of the
Checkpoint 5.6 Q2 (a) P : Microwaves; Q : Visible light; diffracted waves is less.
Q1 (a) The principle of superposition R : X-rays (c)
states that at any time, the (b) P has higher frequency than
combined wave forms of two or radio waves.
more interfering waves is given (c) Photography / Photosynthesis
by the sum of the displacements by plants / Enables human
of the individual waves at each beings and animals to see. (Any
one answer)
point of the medium. (d) R has very high penetrating
(b) (i) power and can cause cancer
2a and genetic defects to living
a cells.
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ANS FOC PHYSICF F4 1P.indd 259 29/01/2020 2:04 PM