Recall Questions
State what is meant by a progressive wave??
A wave that transfers energy from one point in space to another without transferring matter.
Compare transverse and longitudinal waves??
In tranverse waves, the oscillations are perpendicular to the direction of energy transfer. In longitudinal waves, the oscillations are parallel to the direction of energy transfer. They consist of compressions and rarefactions.
Define the displacement of a wave??
Distance from the equilibrium position in a particular direction.
Define the amplitude of a wave??
The maximum displacement of a wave.
Define the wavelength of a wave??
The distance between two points on a wave that are oscillating in phase e.g. peak to peak, or trough to trough.
Define the period of a wave??
Time taken for a wave to move one complete wavelength // The time taken for a point on a wave to complete one oscillation.
Define the frequency of a wave??
The number of complete wavelengths of a wave passing a point per unit time. // The number of oscillations of the medium per unit time.
State the relationship between the frequency and time period of a wave??
$$\text{frequency} = \frac{1}{\text{time period}}$$
State two ways that a wave may be represented graphically??
Displacement-time graphs and displacement-distance graphs.
What is the path difference between two points on a wave, or between two points on different waves??
The fraction of a wavelength by which one point is behind another (which can be caused by one wave travelling further than another).
What is the phase difference between two points on a wave, or two points on different waves??
The fraction of an oscillation by which one point is behind another, measured in radians.
What is the relationship between phase difference and path difference??
$$\text{phase difference} = \text{path difference}\times 2\pi$$
State the law of reflection??
$$\text{angle of incidence} = \text{angle of reflection}$$
State what is meant by refraction??
The change in direction of a wave at a boundary between two materials/mediums.
Explain what causes refraction??
A change in speed of the wave as it travels from one material to another.
What line are angles of incidence, reflection and refraction measured from??
The normal line, drawn perpendicular to the boundary between materials at the point where the wave strikes the boundary.
State what is meant by diffraction??
The spreading of a wave when it passes through a gap or around an obstacle.
What condition is needed to observe maximum diffration of a wave??
The size of the gap or obstacle should be the same size as the wavelength of the wave.
How does the speed, wavelength and frequency of a wave change during diffraction??
They remain constant.
State what is meant by a plane polarised wave??
A wave in which the oscillations are in one plane only.
Which type of wave can be polarised??
Transverse waves.
Describe waht you would ovserve if plane polarised light was passed through a polarising filter which was rotated through 360 degrees??
As the polariser is rotated, the intensity of light passing through would vary between a maximum and zero every 90 degrees.
Define ‘intensity’ of a progressive wave??
The radiant power passing at right angles through a surface per unit area.
What is the relationship between intensity and distance from a point source of power??
Inteinsity is inversely proportional to the square of the distance.
State the relationship between the intensity and amplitude of a wave??
Intensity is porportional to the amplitude of the wave squared.
State the seven parts of the electromagnetic spectrum in order from longest to shortest wavelength??
Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays.
State the range of typical wavelengths for radio waves??
$$10^{-1}m - >10^6m$$
State the range of typical wavelengths for microwaves??
$$10^{-3}m - 10^{-1}m$$
State the range of typical wavelengths for infrared radiation??
$$7\times10^{-7}m - 10^{-3}m$$
State the range of typical wavelengths for visibile light??
$$4\times10^{-7}m - 7\times10{-7}m$$
State the range of typical wavelengths for ultraviolet??
$$10^{-8}m - 4\times10{-7}m$$
State the range of typical wavelengths for X-rays??
$$10^{-13}m - 10^{-8}m$$
State the range of typical wavelengths for gamma rays??
$$<10^{-16}m - 10^{-10}m$$
State five similarities between electromagnetic waves??
- Consist of oscillating electric and magnetic fields.
- Travel through a vacuum.
- Travel at the same speed in a vacuum.
- Are transverse.
- Can be polarised.
How could polarisation of electromagnetic waves be observed??
Using a microwave emitter, microwave receiver and metal grill.
Define the term refractive index of a material??
The ratio of the speed of light in a vacuum to the speed of light in a material.
Which way does light refract when travelling from a low refractive index material to a high refractive index material??
Towards the normal.
Describe changes to the wavelength, frequency, and speed of a wave when it travels from a low refractive index material to a high refractive index material??
Wavelength decreases, frequency remains constant and speed decreases.
Define the critiical angle for a material??
The angle of incidence for which the angle of refraction would be 90 degrees.
State the refractive index of air??
$$1.00$$
State the conditions needed to observe total internal reflection??
The wave must be travelling from a high refractive index material to a low refractive index material at an angle greater than the critical angle.
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date: 2021-08-03 13:47
tags:
- '@?physics'
- '@?public'
- '@?school'
- '@?waves'
- '@?waves-i'
- '@?recall-questions'
title: 'Physics - Recall for Chapter 11: Waves I'