Waves Flashcards
What do waves transfer without transferring matter?
Energy and information
Waves consist of oscillating particles that move about a fixed point.
What are the characteristics of transverse waves?
Have peaks and troughs; vibrations are at right angles to the direction of travel
An example of a transverse wave is light.
What are the characteristics of longitudinal waves?
Consist of compressions and rarefactions; vibrations are in the same direction as the direction of travel
An example of a longitudinal wave is sound.
What is amplitude in wave properties?
The distance from the equilibrium position to the maximum displacement
Amplitude reflects the energy of the wave.
What is a wavefront?
A line joining points on a wave at the same point in their wave cycle at a given time
Wavefronts help visualize the propagation of waves.
Define frequency in the context of waves.
The number of waves that pass a single point per second
Frequency is measured in Hertz (Hz).
What is wavelength?
The distance between a point on one wave and the same point on the next wave
Wavelength is often denoted by the Greek letter lambda (λ).
What does the time period of a wave refer to?
The time taken for one complete wave to pass a fixed point
Time period is the inverse of frequency.
What is the formula for the speed of a wave?
speed = frequency x wavelength
This relationship shows how speed, frequency, and wavelength are interrelated.
How is frequency related to the time period?
frequency = 1 / time period
Frequency is measured in Hertz (Hz).
What happens to waves when they travel from a medium of low optical density to one of higher optical density?
They can be reflected
The law of reflection states that angle of incidence = angle of reflection.
What remains unchanged during the reflection of waves?
Frequency, wavelength, and speed
Reflection occurs without altering these wave properties.
What occurs during the refraction of waves?
The speed of a wave changes when it enters a new medium
Refraction involves bending of waves based on medium density.
What happens to a wave’s speed when it enters a denser medium?
Its speed decreases and it bends towards the normal
This is due to the change in optical density.
What happens to a wave’s speed when it enters a less dense medium?
Its speed increases and it bends away from the normal
This bending is a result of the change in optical density.
Fill in the blank: The angle of incidence equals the _______ during reflection.
angle of reflection
This principle is fundamental in understanding wave behavior.
What stays the same in electromagnetic waves while the wavelength changes?
Frequency
The frequency remains constant while the wavelength varies, leading to a change in velocity.
List the main groups of the electromagnetic spectrum in order of decreasing wavelength.
- Radio
- Microwave
- Infrared
- Visible
- Ultraviolet
- X-Ray
- Gamma Ray
The visible spectrum colors are ROYGBIV (Red, Orange, Yellow, Green, Blue, Indigo, Violet).
What is the speed of electromagnetic waves in a vacuum?
The same high speed
All electromagnetic waves travel at approximately the same speed in air as well.
What are radio waves primarily used for?
Radio and television communications
Radio waves have long wavelengths and are reflected by the ionosphere.
What applications do microwaves have?
- Satellite transmissions
- Cooking
Microwaves can penetrate deep into food due to their greater frequency.
What is infrared radiation used for?
Heaters and night vision equipment
In what applications is visible light utilized?
- Fibre optics
- Photography
What is ultraviolet light used for?
Fluorescent lamps
What are X-rays used for?
- Medical imaging
- Security
X-rays can penetrate materials easily due to their short wavelength and high frequency.
What is gamma radiation used for?
Sterilising food and medical equipment
What hazard is associated with microwaves?
Internal heating of body tissues
What can infrared radiation cause?
Skin burns
What are the risks of ultraviolet light exposure?
- Increases risk of skin cancer
- Risk of blindness
Sun cream and sunglasses can help prevent over-exposure to UV light.
What type of radiation are X-rays and gamma rays classified as?
Ionising radiation
What can ionising radiation cause?
Mutations leading to cancer
How should exposure to X-rays and gamma rays be minimized?
Using protective shielding made of very dense materials such as lead
What type of waves are light waves?
Transverse waves
What phenomenon occurs when light reflects at a plane mirror?
Formation of an image
What is represented by a ray diagram in reflection?
Light reflecting at a plane mirror
What happens to light when it passes through a glass slab at an angle?
Refraction occurs
When light enters a more optically dense medium, what is true about the angles?
Angle of incidence is greater than angle of refraction
What is Snell’s law used for?
Relates angle of incidence and angle of refraction to refractive index
Fill in the blank: Snell’s law is represented by _______.
nsini = n2sinr
What is the critical angle in the context of total internal reflection?
Angle of incidence where light travels along the boundary
What condition must be met for total internal reflection to occur?
Angle of incidence must be greater than the critical angle
From which medium to which medium must light travel for total internal reflection?
From more optically dense to less optically dense
How is the critical angle related to the refractive index?
n = sin(sin c)
What is an optical fibre?
A long thin rod of glass surrounded by cladding
What principle do optical fibres use to transfer information?
Total internal reflection
In what fields are optical fibres extensively used?
Medicine and communications
What are two applications of optical fibres in medicine?
Endoscopes, inside-body flexible cameras
What is one application of optical fibres in communications?
High-speed data transfer
What type of waves are sound waves?
Longitudinal waves
Longitudinal waves are waves in which the displacement of the medium is in the same direction as the wave propagation.
What two phenomena can sound waves undergo?
Reflected and refracted
Reflection occurs when a wave bounces off a surface, while refraction is the bending of waves when they enter a medium at an angle.
