Physics Module Waves

Physics Module – Waves (by nick SMSHS) 1

Physics Module – Waves (by nick SMSHS)

6.1 UNDERSTANDING WAVES

1. Two types of waves :i. Transverse waveii. Longitudinal waves

A. Transverse wave

(i) Transverse wave is a wave in which the vibration of particles in the medium is at perpendicular to the direction of propagation of the wave.

A = crest B = trough

(ii). Example of transverse wave:

i. ………………………………………

ii…………………………………………

iii……………………………………… …

B. Longitudinal waves

(i) A longitudinal is a wave in which the vibration of particles in the medium is parallel to the direction of propagation of wave.

P = compression Q = rarefaction

(ii) Example of longitudinal wave : …………………………..

A wave front is a line or plane on which the vibration of every points on it are in phase and are at the same position/distance from the source of the water.

Two types of wavefront: (from the top view)i) Circular wavefront ii) plane wavefront

dipper

A A

BB

P P

Q Q

2


Amplitude, Period and Frequency of a Wave

1. Equilibrium position is …………………………………………………………….

2. One complete oscillation of the pendulum occurs when the pendulum bob moves from ……

3. The period, T of a vibrating system is ……………………………………………... 4. Frequency, f is …………………………………………… The S.I. unit is ……………..

f =

1T or f =

nt

5. Stroboscope is use to …………………………………….. Stroboscope frequency = number of slits x rotation frequency of stroboscope or

6. Wave speed, v = f λ λ = wavelength of the wave

Exercise 6.1

Figure 6.10

7. (a) The wavelength of the wave in the diagram above is λ(b) The amplitude of the wave in the diagram above is A

8. Indicate the interval which represents one full wavelength.

Answer: ……………………

Figure 6.11

A

B

C A

B

C

0 0

f = np

A-B-C-B-A

the position of the object where is no resultant force acts on the object.

freeze waves patterns on the screen

the time taken to complete an oscillation

the number of complete oscillations Hertz (Hz)

3

Physics Module – Waves (by nick SMSHS) 4

5

-5

2 4

Displacement/cm

6 Time/s0

Displacement/cm

6

Distance/cm2 4

5

-5

•

6.0 cm

•4.5 cm


Exercise 6.11 1. In an experiment , Lim observes that a simple pendulum completes 30 oscillations in 15.0 seconds. What is (a) the frequency of oscillation? (b) the period of oscillation?

(a) f = 30/15 = 2 Hz2. Calculate the frequency of the given wave below

. Answer : T = 4s f = Hz3. Based in the displacement-distance graph of a wave, find (a) the amplitude (b) the wavelength of the wave

= 0.25 Hz

4. A transverse wave is found to have a distance of 4 cm from a trough to a crest, a frequency of 12 Hz, and a distance of 5 cm from a crest to the nearest trough. Determine the amplitude, period, wavelength and speed of such a wave.

5. A girl moves a long slinky spring at a frequency of 3 Hz to produce a transverse wave with a wavelength of 0.5 m. What is the wave speed of the waves along the slinky spring?

6. The figure shows a wavefront pattern in a ripple tank produced by a vibrating dipper at frequency of 5 Hz. What is the wave speed?

7. The figure shows a wavefront pattern in a ripple tank produced by a vibrating dipper at frequency of 5 Hz. What is the wave speed?

0

5

20 cm (5)


7.5 8. A mechanical stroboscope has 12 slits and rotates

at a frequency 5 Hz. The stroboscope is used to observe water waves. The observer notes there are 6 successive bright bands at a distance 20 cm. Calculate the speed of the water waves.

9. The figure shows a loudspeaker produces a sound with a frequency 300 Hz. Calculate

(a) the wavelength.(b) the speed of sound

10. A given wave travels at a speed of 2 x 105 ms-1. If the frequency of the wave is 1000 Hz, Calculate the wavelength

11. (a) Base on the figure determine, (i) the amplitude (ii) the wave length (b) What is the frequency of the sound if the speed of sound is 330 ms-1 == 200 m

Answer: (a) (i) 2 cm

(ii) 50 cm

(b) f = v / = 330 / 0.5 = 660 Hz

6

A

B

C

D

E


Damping

Figure 6.12

1. Damping is a …………………………………………………………………………..

2. When a system is damped , the amplitude of the of oscillation decreases slowly until the system stops oscillating.

3. Damping is usually caused by :-(i) external frictional forces such as air resistance (ii) internal forces , where energy is lost from the system in form of heat.

R esonans

A resonance is ………………………………………………………………………………………

………………………………………………………………………………………………………..

Experiment to show a phenomenon of resonance

Figure 6.12: Barton’s pendulum

Pendulum B and D are the same length. When pendulum B oscillates, all the pendulum start to oscillate. But pendulum B and D have the same length, so there have same natural frequency. So pendulum D will oscillates with maximum amplitude.

7

Water waves

Ripple tank

Screen


6.2 ANALYSING REFRLECTION OF WAVES

1. Reflection of a wave occurs when a wave strikes an obstacle such as barrier, plane reflector, mirror and wall.

2. The reflection of waves obeys the law of reflection : ………………………………………………………………………………………………………………………………..

Exercise 6.2

Complete the diagram below.

Reflection of water waves 1. Show the pattern of the reflection of the water waves

(b)

2. Show the dark and bright pattern on the screen below.

Reflection of Light Wave

(i) The angle of incidence is equal to the angle of reflection.(ii)The incident wave, the reflected wave and the normal lie in the same plane.

8

(a)

(b)


1. When rays of light strike any surface the rays are reflected , unless the surface is black, when they are absorbed.

2. A plane mirror is a flat smooth surface which reflects regularly most of the light falling on it.

Figure 6.20

3. The characteristics of reflection of light waves:

…………………………………………………………………

4. The bright and dark bands of the wave pattern formed on the screen because the surface of water acts as lenses. The crest of water waves similar with convex lens and the trough of water waves similar with concave lens.

Exercise 6.21

The diagram shows a single ray of light being directed at a plane mirror. What are the angles of incidence and reflection?(a) (b)

(b)

R eflection of sound waves

35o

9


1. The sound waves is reflected by walls and ceilings of buildings, unborn baby or sea bed.

Figure 6.21 2. The sound wave from the stopwatch experience a reflection after striking the smooth wall. The angle of incidence, i is equal the angle of reflection, r.

Exercise 6.22

1. The diagram shows a student shouting in front of a school building. Calculate the time taken by the student to hear the echo of his voice.

[The speed of sound in air is 340 m s-1 ]

2.

If an echo is heard one second after the holler and reflects off canyon walls which are a distance of 170 meters away, then what is the speed of the wave?

6.3 ANALYSING REFRACTION OF WAVES

10


1. The refraction of water waves occur when there is a ………………………………………

2. After refraction, the wave has the same ……………… but a different ……………………………………

Refraction of Water Waves

Deep shallow

Figure 6.31

1. When the water wave travel from a deep area, the direction of the waves is refracted ……… (towards/away from) the normal.2. The angle of incidence, i of the water is ………….. (greater / smaller) than the angle of refraction, r3. When the refraction of a wave happened , the frequency, f does not change but the

………………............................................................................... of the wave change.

Exercise 6.3

On each of the following diagram, draw the refracted wave by the perspex.

(a) (b)

frequencyspeed, wavelength and direction.

11


(c) (d)

(e) (f)

Refraction of water wave of the sea water

1. Why are the speed and wavelength of waves in the middle of the sea almost uniform?

……………………………………………………………………………………… 2. What do you think would happen to the wave speed if the depth of water is increased?

……………………………………………………………………………………….3. Why do the distances between the wavefronts decrease as the waves approach the beach?

……………………………………………………………………………………………

4. Why is the water in the bay stationary compared to the water at the cape?

………………………………………………………………………………………

Refraction of Light Waves

12


Figure 6.33

1. When a ray propagates from one medium to an optically denser medium, the ray refracts …………………(towards / away from) the normal.

2. The speed of light …………….(decreases/increases) as it propagates in the glass block, causing it to alter the direction of propagation.

Refraction of Sound Waves

Figure 6.34 (a) Figure 6.34 (b)

1. Sound waves travel faster in warm air than in …….. (cold/hot) air.

2. On a hot day, the hot surface of the Earth causes the layer of air near the surface to be ………… (warmer/cooler)

3. This causes sound waves to be …………. (reflected/refracted) away from the Earth.

4. On a cool night, the sound waves travel ………….(slower/faster) in the cooler layer of air near the surface of the Earth than in the upper, warmer air. The waves are refracted towards the Earth. Hence, sound can be heard over a longer distance on a cold ……….(night/day) compared with a hot day.

glass block

normalair

13


6.4 ANALYSING DIFFRACTION OF WAVES

1. Diffraction of waves is ……......................................................................................................2. The effect of diffraction is obvious only if (a) the size of the aperture or obstacle is small enough. (b) the wavelength is large enough.3. Frequency, wavelength and speed of waves do not change4. The amplitude of the waves are change Exercise 6.4 Complete the diagrams below by drawing the wavefronts to show the diffraction of water waves.

From the diagram above,1. The narrower the gap, the more the waves spread out.2. When the gap is much wider than the wavelength of the waves, there is little diffraction.

Diffraction of light waves

Figure 6.40 Difraction of light through a single slit

(b) Wider gap > λ(a) Narrow gap ≤ λ

(d) Narrow obstacle (c) Wider obstacle

14


Figure 6.41 (a) Figure 6.1(b) Narrow slit Wide slit

1. The diffraction of light waves occur when the light waves pass through a small slit or small pin hole.2. The wider middle bright fringe shows that the light waves diffracted after pass through a narrow slit.1. If the slit becomes wider, diffraction pattern becomes ………….. (less/more) distinct.

Diffraction of sound waves

Figure 6.42

1. A listener is requested to stand on the other side of the corner of the wall so that the radio is beyond his vision.

2. The listener is able to hear the sound of the radio although it is behind the wall.3. t is because the sound of the radio spreads around the corner of the wall due to diffraction of sound.

6.5 ANALYSING INTERFERENCE WAVE

1. Interference is the superposition of two waves from two coherent sources meet

2. Two waves are in coherent if they are of the same …………………. and …………………...

3. There are two types of interference :

i) ……………………………………………

ii) ……………………………………………

Bright at the centre

15


Principle of superposition

1. The principle of superposition states that………………………………………………………

…………………………………………………………………………………………………

2. Constructive interference occurs when………………………………………………….………

…………………………………………………………………………………………………

3. Destructive interference occurs when…………………………………………………………

…………………………………………………………………………………………………

4. (a) Constructive Interference

+ =

Before superposition During superposition

Figure 6.50 (a)

+ =


Figure 6.50 (b)

When the vertical displacemet of two waves are in the same direction as in Figure 6.50

(a) and (b), …………………………(constructive/destructive) interference occurs.

(b) Destructive Interference

+ =


Figure 6.51

If a wave with a positive displacement meets another with a negative displacement of the same magnitude, they cancel each other and the combined amplitude becomes ………………..

16


Inteference of Water Waves

Figure 6.52: Inteference of water waves

1. At the points of constructive interference, the water moves up and down with a

………… (large/ small) amplitude

2. The points of constructive interferences, is known as ……………. ( nodes/antinodes)

The points of destructive interferences is known as ……………… (nodes/antinodes).

Exercise 6.5

Figure 6.53

1. Figure 6.53 shows the interference pattern of water by two coherent sources of water waves.

(i) At point A, two crest meet resulting in ……………………….. interference.

(ii) At point B, two through meet resulting in ……………………..interference.

(iii) At point C, a crest meet a trough resulting in …………………interference.

A

BC

17


2. Complete the table below.

Before superposition During superposition After superposition

3. Categorize each labeled position as being a position where either constructive or destructive interference occurs.

i) Constructive interference: ……………………. ii) Destructive interference: ………………………

. 2. The diagram shows a full-scale interference pattern of a ripple tank experiment 2

seconds after vibration started. The crests of the water ripples are repsented by the dark lines.

(a) What is represented at P at this instant?

………………………………………………………………………………………

(b) What is the frequency of the vibrator?

………………………………………………………………………………………

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5. Two dot vibrators which has a separation of 5.0 cm are placed on a water surface in a ripple tank. The distance between two adjacent antinodes on a screen is 3.0 cm. If the perpendicular distance between the dot vibrators and the screen is 10.0 cm, what is the wavelength of the water waves?

Answer:

Inteference of Light Waves

1. Interference occur when at least two coherent light waves overlap or superpose

2. The superposition of 2 rays produces:

(i) ……………………………………… (ii)…………………………………

3. When constructive occurs there will be a ………… (bright/dark) fringe

When destructive occurs there will be a …………(bright/dark) fringe 4. The wavelength of monochromatic light can be found by the formula:

a = …………………………………………………..

x = ………………………………………………….

D = ………………………………………………….

constructive interference destructive interference.

19

14 mm


Exercise 6.51

1. In a Young’s double slit experiment, a light of wavelength 633 nm passes through two slit which are 0.5 mm apart. Vertical fringes are observed on a screen placed 4 m from the slits.

(i) Calculate the distance between two adjacent bright fringes.(ii) What will happen to the distance between two adjacent bright fringes if a light of

shorter wavelength is used?

2. The wavelength of light can be determined with a double-slit plate. The diagram above shows the pattern of interference fringes obtained in a Young’s double-slit experiment. The separation distance of the two slit is 0.20 mm and the distance between the screen and the double-slit plate is 4.0 m. Calculate the wavelength of the light used in the experiment.

Answer :

20


Inteference of Sound Waves The wavelength of sound wave can be found by the formula: a = ………………………………………………….. x = …………………………………………………. D = ………………………………………………….

Exercise 6.52

1. Two loud speakers placed 2 m apart are connected to an audio signal generator that is adjusted to produce sound waves of frequency 550 Hz. The detection of loud and soft sounds as a person moves along a line is at 4.0 m from the loudspeakers.

Calculate the(a) wavelength(b) speed

of the sound waves.

Answer: = 550 x 0.6 = 330 m s-1

Analysing Sound Waves

1. Sound waves are longitudinal wavces which require a medium for its propagation.

2. The loudness of the sound is depend to the amplitude …………………

3. The pitch of the sound is depend to the ………………………………………………………… 4. Echo is ………………………………………………………………………………………….Application of Sound Waves

frequenc

21


1. Ultrasonic waves with frequencies above 20 kHz cannot be heard by human ear.2. The ultrasonic ruler is used to measure the distance between itself and a target.3. The depth of sea water can be calculated using the formula : 2d = v x t

Exercise 6.60

1. In an expedition to determine the depth of a freshwater lake using an ultrasonic ruler, a pulse of ultrasonic sound is generated and travels to the bottom of the lake and reflected by it. The time taken by the pulse to travel to the bottom of the lake and return to the ruler is 0.35 s. If the speed of sound in freshwater is 1482 m s-1, calculate the depth of the lake.

Answer:

Analysing Electromagnetic Waves

1. The electric and magnetic field vibrate …………………….. (perpendicular/parallel) to each other and to the direction of propagation.

2. Properties of electromagnetic waves

(i) ..........................................................................................................................................

(ii) ..........................................................................................................................................

(iii) ..........................................................................................................................................

(iv) ..........................................................................................................................................

3. Sources and applications of electromagnetic waves in daily life

Type of em wave Source Application

Radio waves = 10-1 - 105 m

(a)

Microwave = 10-3 – 10-1 m

(a)

Infrared = 10-6 – 10-3 m

(a)

Visible light = 10-7 m

(a)

Ultraviolet radiation = 10-9 – 10-7 m

(a)

X-ray = 10-11 – 10-9 m

(a) Radiotherapy(b) Detection of cracks in building ructures

Gamma rays = 10-14 – 10-10 m

(a)

Exercise 6.70

22


1. The diagram below shows the pattern of spectrum electromagnetic. In the boxes provided, write the names of the parts given .

2. Table 6.70 shows electromagnetic waves P, Q, R and S and their uses

Electromagnetic waves UsesP Remote controlQ Radar systemR PhotographS Kill cancerous cells

Table 6.70

Identify P, Q, R and S

Answer: P = Infra-red rays Q = Microwaves

Gamma ray

X-ray

UltraViolet

Visible light

infrared

microwave

wavelength

frequency

23


1. What will happen to the total energy of an oscillating system which is oscillatingat its natural frequency without damping?

A Increases B DecreasesC Remains constant

2. The figure shows five pendulums that are hung along the wire MN. The pendulum P is displaced and then released.

Which of the pendulums will oscillate with the highest amplitude?

A Pendulum WB Pendulum X

C Pendulum YD Pendulum Z

3. Diagram below shows displacement-distance graph of a loaded spring which isvibrating with a frequency 10 Hz.

What is the velocity of the vibration?

A. 60 ms-1. B. 40 ms-1. C. 30 ms-1

D. 20 ms-1. E. 10 ms-1.4. Which graph shows the relationship between frequency,f and period, T of a wave?

24

X

T

S

R

Q


A f

T

B f

TC f

T

D f

T

5. The diagram shows the transverse waves with point X.

Where would point X be after half a period?

A Q B R C S D T

6. Which of the following is a correct example of a longitudinal wave and of a transverse wave ?

Longitudinal Wave Transverse WaveA Gamma Ray LightB Sound Gamma RayC Light RadioD Radio Sound

7. The diagram shows a displacement-distance graph of a wave.

25

A

C

D

E

F

B


What is the amplitude of the wave, in m ?

A 16 B 20 C 32D 40 E 80

8. The diagram shows a type of transverse waves.

Which of the following pair of points is the wavelength of the wave?

A AC B BDC BE D AF

9. Diagram shows transverse waves formed by a rope.

What is the wavelength and amplitude of the wave?

Wavelength AmplitudeA 30 cm 20 cm B 40 cm 10 cmC 40 cm 20 cm

D 80 cm 10 cm

26


10. The Diagram shows a ball floating in a water tank.

Which of the following is the correct movement of the ball, when the wave passes?

11. A dipper vibrates produces waves in a ripple tank. What happen if the frequency of the dipper is increased?

A. The wavelength of the wave decreasesB. The amplitude of the wave increasesC. The speed of the wave increases

12. Which of the following will change when water waves pass through a narrow gap?

A FrequencyB AmplitudeC SpeedD Wavelength

13. The diagram shows a displacement- time graph of water waves.

27

L-shaped barrierHalangan berbentuk L


Which of the following is true?

A The period of the water wave to vibrate is 25 sB The amplitude of the water wave is 0.4 mC The frequency of the water wave is 0.05 HzD The wavelength of the water wave is 20 m

14. Diagram shows plane water waves travelling towards an L-shaped barrier in a ripple tank.

Which diagram shows the reflected wave pattern?

A B

C D

15. Diagram shows a boat behind a concrete barrier.

28

Boat

Concrete barrier


When the sea waves approach the barrier, the boat is seen moving up and down. This is because the sea waves undergo

A reflection B refractionC diffraction D interference

16. Diagram shows plane waves moving towards a slit.

The motion of the waves through the slit will cause a change in the

A amplitude / amplitudB wavelength / panjang gelombangC wave speed / laju gelombangD frequency / frekuensi

17. The diagram shows the wave when it passes through a narrow gap.

Which of the following below can cause angle θ to increase

A the width of the gap decreases B the wave length decreasesC the frequency increasesD water in the ripple tank is shallower

18. Which pattern shows effect of diffraction ?

29


A

B

C

D

19. A wave with a frequency of 12 Hz travels with a velocity 36 cm s-1. What is the distance between the two consecutive amplitudes of the wave?

A 1.5 cm B 3.0 cm C 4.5 cm D 6.0 cm

E 7.5 cm

20. The diagram shows a superposition of two waves.

30

Direction of the wave

10.0 cm


Which of the following positions has the maximum amplitude?

A K and N B M and N C L and N D M and K

21. The diagram shows a longitudinal wave travels with the velocity of 36 cm s-1.

What is the frequency of the wave?

A 0.5 Hz B 1.8 Hz C 3.6 Hz D 180.0 Hz E 360.0 Hz

22. In a Young’s Experiment, when the wave length of a green light with 5.0 x 10 - 7 m is used, the distance between consecutive fringes is 0.40 mm. If this experiment is repeated using a X light, the distance between consecutive fringes is 0.48 mm Therefore the wave length of X light is …

A 2.4 x 10 – 7 mB 4.2 x 10 – 7 mC 5.0 x 10 – 7 mD 6.0 x 10 – 7 mE 7.0 x 10 – 7 m

31

X Y Z

Displacement

Time

S

T


23. Diagram shows diagrams of different fringes are formed on the screens when three different sources of light X, Y and Z are used in Young’s double-slit experiment.

Which of the following shows the probable sources of light?

X Y ZA Green Yellow BlueB Blue Green YellowC Blue Yellow GreenD Yellow Green Blue

24. The diagram shows a displacement-time graph of two notes S and T.

Which of the following statement is true ?

A S is louder but has a lower pitch.B S is louder and has a higher pitch.C T is louder but has a lower pitch.D T is louder and has a higher pitch.

32

X Y

Spherical dipper

Wooden blockWater tank

X Y

X Y

X Y

X Y


25. A trumpet and a flute are played by two students. The note from the trumpet is louder and has a lower pitch than the note from the flute.How do the amplitude and frequency of the sound from the trumpet compare to the amplitude and frequency from the flute?

trumpet’s amplitude trumpet’s frequency

A larger higherB larger lowerC smaller higherD smaller lower

26. The diagram shows a spherical dipper is vibrating on the water surface of a tilted water tank

Which of the following wave patterns will be observed in the water tank?

A

B

C

D

33

Shallow regionKawasan cetek

Deep regionKawasan dalam


27 Diagram shows water waves moving towards a narrow gap.

What are the phenomena that occur when the water waves pass through the gap into the shallow region?

A Refraction and diffraction / Pembiasan dan pembelauanB Reflection and refraction / Pantulan dan pembiasanC Reflection and diffraction / Pantulan dan pembelauan

28. A girl can hear the voices of two people talking around the corner but she cannot see these people because

A Sound waves are reflected better than light waves.B Sound waves are refracted better than light waves.C Sound waves are diffracted better than light waves.D Sound waves are interfered better than light waves.

29. Diagram shows a wave moving into shallower water.

The wavelength of the waves is reduced because

A frequency and the speed decreaseB frequency and the speed increaseC the frequency increasesD the speed decreases

34


30. Water waves travel more slowly as they move from deep to shallow water in a ripple tank. Which diagram shows the refraction of the waves?

31. Which diagram correctly shows water traveling through deep water to shallower water?

35


32. The diagram shows wave fronts that move towards the beach from the sea. It is observed that the sea is calmer at the bay than at the cape.

The phenomenom seen in diagram is

A interferenceB reflectionC diffractionD refraction

33. Radio waves are received at a house at the bottom of a hill.

The waves reach the house because the hill has caused them to be

A diffracted / dibelauB radiated / diradiasiC reflected /dipantulD refracted / dibias

34. A pinhole camera is used to observe a ray of light. Which of the following shows the result?

36


35. Which of the following pattern formed when water waves pass through a narrow gap or a small obstacle in a ripple tank.

36. A vibrator produces 20 waves per second. If the frequency of the vibrator is doubled, the wave length of the waves will beA ¼ of the original wave lengthB ½ of the original wave length C 4 times of the original wave lengthD twice the original wave lengthE equivalent to the original wave length

37. Diagram below shows interference pattern which is obtained from anexperiment using monochromatic light. The screen is located at 3 m from thedouble slit, while the double slit separation is 0.5 mm.

If the wavelength of the monochromatic light is 6.5 x 10-7 m, what is the value of y?A. 1.3 x 10-3 m B. 3.9 x 10-3 m C. 7.8 x 10-3 m

D. 9.75 x 10-3 m E. 11.7 x 10-3 m

38. In an experiment of light interference, the distance between two consecutive bright fringes ,x varies with distance between double slit and screen, D. Which of the following graph shows the correct relationship between x and D?

37


39. The diagram shows an inteference pattern of water waves from two coherent sources X and Y.

Which of the points, do costructive inteference occur ? A A, B and CB A, B and DC A, C and DD B, C and D

40. The diagram shows an interference pattern of two coherent water waves of sources, P and Q.Gambar rajah menunjukkan corak interferens bagi dua sumber gelombang air P, dan Q, yang koheren.

Which of the positions A, B, C or D, does destructive interference occur ?Antara kedudukan A, B, C atau D, yang manakah berlakunya interferens memusnah?

41. Diagram shows two consecutive photographs of a loudspeaker with a lighted candle in front of it.

The observations on the candle flame show that sound waves are

A transverse waves / gelombang melintangB longitudinal waves / gelombang membujurC polarized waves / gelombang berkutubD electromagnetic waves / gelombang elektromagnet

38

R

R S T

Loudspeaker

Receiver aerial

ABCD


42. P,Q,R,S,T are parts of the electromagnet waves which have been arranged according to the wave length in ascending order. If R is the white light, which of the following statements is true?

A Area S has X-rays B Area P has gamma raysC Area Q has micro waves D Area T has a high frequency waves

43. Which of the following colours have the shortest wavelength ?

A PurpleB BlueC GreenD Red

44. The diagram shows a modulated wave transmitted through the aerial. Which of the following statements is true regarding the modulated waves?

A The frequency of the radio waves vary according to the audio signals. B The amplitude of the radio waves vary according to the audio signals.

C The frequency of the modulated waves varies according to the frequency of the radio waves.

45. The diagram shows a block diagram of a radio wave receiver.

What do Q, R, S and T represent?

39


46. A VHF (Very High Frequency) radio station broadcasts at a frequency of 90 MHz. The speed of radio waves is 3 x 108 ms-1. What is the wavelength of the waves broadcast by the station?Sebuah stesen radio VHF (Frekuensi Lampau Tinggi) memancarkan gelombang pada 90 MHz. Laju gelombang radio adalah 3 x 108 ms-1. Berapakah panjang gelombang, yang di pancarkan oleh stesen radio itu?

A. 0.3 mB. 3.3 mC. 6.0 mD. 8.0 mE. 9.0 m

47. Azimah shouts infront of a high wall. She hears the echo of her voice 1.5 seconds later. The velocity of sound in air is 340 ms-1. What is the distancebetween Azimah and the wall?

A 204 mB 283 mC 340 mD 510 mE 816 m

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