Chapter 1 : Waves

1.1 Understanding waves

Motion of waves

1. Waves : transfer __________ from one point to another without transferring __________

2. Oscillating motion / vibrating motion – A point or body moves __________ and __________ along a line about a fixed _______________ >> produces wave

3. Examples of waves:- __________________ : vibration of electrons in an atom- __________________ : vibration of mechanical bodies- __________________ : disturbance on a still water surface

Propagation of Waves When a wave travels through a medium, the particles of the medium

__________ about their ____________________. The particles of medium do not travel in the direction of wave. Wave transfers __________ and the __________ from the source of the

wave to the surroundings.

Wavefront = line that joins all the points that are vibrating in-phase (same direction with the same displacement) and at the same distance from the source

Chapter 1 : Waves

Types of Waves Transverse wave

Vibration of particles in the medium is perpendicular to the direction of the propagation of the wave

E.g. water waves, light waves

Longitudinal wave

Vibration of particles in the medium is parallel to the direction of

the propagation of the wave E.g. sound waves

Chapter 1 : Waves

1. How does energy move?

2. True or false: the particles in a wave move from where the wave starts to where the wave ends up.

3. What is having work done on it in a wave?

4. What are the two type of waves?

5. The particles vibrate in the same direction as the wave?

6. The particles vibrate perpendicularly to the direction of the wave?

7. What does wavelength mean?

8. What does amplitude mean?

9. Which of the following has the longer wavelength?

 

10. Which of the following has the larger amplitude?

Chapter 1 : Waves

Chapter 1 : Waves

Displacement-time Graph

__________ : maximum displacement from its equilibrium position__________ : highest point of the wave__________ : lowest point of the wave__________ : distance between two successive points of the same phase in a wave

Displacement-distance Graph of a Wave

__________ : time taken to complete an oscillation__________ : number of complete oscillations made by a vibrating system in

one second

Chapter 1 : Waves

Relationship between Speed (v), Wavelength (λ) and Frequency (f)

v = f λ

Velocity (m s-1) = Frequency (s-1) × Wavelength (m)

Damping

Damping = decrease in the __________ of an oscillating systemDamping causes:- amplitude to decrease

- _________ of the system to decrease (as heat energy) - _________ does not change !

Vacuum no damping, oscillates at same amplitude. Normally, oscillation undergoes damping, the amplitude of oscillation

decreases until zero (oscillation stop). External damping of the system = loss of energy to overcome

___________________ or ____________________. Internal damping of the system = loss of energy due to __________ and

__________ of the molecules in the system To oscillate continuously, an external force must be applied to the

system. This motion is called ____________________. Natural frequency = frequency of a system which _________________

without the action of an __________

Resonance

Resonance = a system is made to oscillate at a frequency equivalent to its natural frequency by an external force

The resonating system oscillates at its ____________________. E.g. Oscillation of pendulum, musical instruments, collapsing of bridge,

radio / television tuner

Chapter 1 : Waves

1.2 Reflection of Waves

1. Reflection of waves – occurs when a wave strikes an ___________________________ – wave before it strikes the obstacle__________________ – wave that changed in direction of propagation after reflection

2. Laws of reflection Angle of incidence, i Angle of reflection, r The incident wave, the reflected wave and the normal lie on the

_________________ which is _________ to the reflecting surface at the point of incidence

3. Applications of reflection of waves in daily life

Chapter 1 : Waves

1.3 Refraction of Waves

1. Refraction – occurs when _________of a wave changes, as it moves from one medium to another

– same _________

– different _________, _________and _________

2. Refraction of water waves

3. Refraction of light waves

4. Refraction of sound waves

Chapter 1 : Waves

1.4 Diffraction of Waves

1. Diffraction – waves ___________ as they pass through an _________ or a small round _________ – effect depends on the __________________ and _________ – same _________, _________, _________ – different _________ and __________________ of waves

2. Diffraction of water waves

3. Diffraction of light

Chapter 1 : Waves

4. Diffraction of sound waves

Chapter 1 : Waves

4.3 Interference of Waves

1. Principle of superposition : wave displacement of the combined motion of any number of interacting waves at a point is the __________________of all the component waves at that point

2.

3. Interference = _________of two waves originating from two coherent sources (same _________, _________, same _________)

__________________= crests or troughs of both waves coincide to produce a wave with crests and troughs of maximum amplitude__________________= crest of one wave coincides with the trough of the other wave, thus cancelling each other, causing resultant amplitude to be zero

_________= the point where constructive interference occurs_________= the point where destructive interference occurs

Chapter 1 : Waves

4.4 Sound Waves

1. Properties of sound waves Longitudinal waves Cannot travel through _________ Mechanical waves Produced by _________of matter Produces ___________and ___________ Speed of sound travelling in gas depends on mass of _____________ Speed of sound : Gases < Liquid < Solid

2. Loudness <<<< _________Pitch <<<< _________

3. Quality of sound <<<< sound waveform. Different musical instruments produce sounds of different waveforms, hence of different qualities.

Chapter 1 : Waves

4.5 Electromagnetic Waves

1. Electromagnetic wave = propagating waves in space with _________ and _________ component (oscillates at right angles to each other and to the direction of propagation)

2. Properties of electromagnetic waves: Transfer _________ from one point to another Transverse wave Can travel through a _________ Travel at the same speed through a vacuum, at the speed of _________ Show normal wave properties Can be polarized.

3. Polarisation of light Polarisation of light = process of confining the vibrations of a light wave

in only one plane which is perpendicular to the direction of travel of wave

Can be done by using polaroid film

Chapter 1 : Waves

4. Electromagnetic spectrum Classifies electromagnetic waves according to _________

5. Detrimental effects of excessive exposure to radiations Mircowaves : internal heating of body tissue, brain tumor, ear

complications Infrared : skin burns Visible light : premature skin aging, skin cancer Ultraviolet waves : damage to surface cells (skin cancer), blindness X-rays : damage to cells Gamma rays : cancer, mutation