4.4 - Waves Flashcards
What is a progressive wave?
A wave that moves away from a source and transfers energy from one place to another without any net transfer of matter.
Define ‘longitudinal wave’.
A progressive wave where the vibrations are parallel to the direction of energy transfer (resulting in the formation of compression and rarefaction).
Define ‘transverse wave’.
A progressive wave where the vibrations are at right angles to the direction of energy transfer.
Give 3 examples of longitudinal waves.
Sound
Ultrasound
Certain types of seismic waves called P waves
Give examples of transverse waves.
Any EM spectrum wave, heat, surface waves.
Define “Displacement”.
The distance any part of the wave has moved from its mean (rest) position - it can be positive or negative.
-Measured in METRES
Define “Amplitude”.
The maximum displacement - the distance from a peak or trough to the mean (rest) position.
-Measured in METRES
Define “Wavelength”.
The distance between two successive identical points that have the same pattern of oscillation.
- Measured in METRES
Define “Period”.
The time it takes for one complete pattern of oscillation to take place at any point.
- Measured in SECONDS
Define “Phase Difference”.
The relationship between the pattern of vibration at two points.
- Measured in RADIANS
Define “Frequency”.
The number of oscillations per unit time at any point.
- Measured in HERTZ (Hz)
How would you work out the period on an oscilloscope?
Period = Distance between peaks x Time Base Setting
Define wave INTENSITY.
The rate at which energy is transferred from one location to another as wave travels through space, PERPENDICULAR to the direction of wave travel.
If the power in a wave spreads out equally in all directions, what is the formula?
Intensity = Power /4πr^2
Describe how INTENSITY and AMPLITUDE relate to each other.
The amplitude of a wave decreases as the wave spreads out from a source. The energy of a wave is proportional to the square of its amplitude. Hence the intensity of a progressive wave is also proportional to the square of its amplitude:
I ∝ A^2
What can all waves experience (3) ?
REFLECTION
REFRACTION
DIFFRACTION
What are 7 properties of ELECTROMAGNETIC waves?
- They can all travel through a vacuum
- All possess both a magnetic wave and an electrical wave interlocked and at right angles to each other.
- In free space, they all travel at the speed of light, 2.98 x 10^8 ms^-1
- They are all TRANSVERSE waves
- They can all be REFLECTED, REFRACTED and DIFFRACTED.
- They can all demonstrate INTERFERENCE.
- They can all be POLARISED.
What is the range of Wavelength (m) of RADIO?
What is its range of Frequency (Hz)?
10^-1 - 10^4 m
3 x 10^9 - 3 x 10^4 Hz
Give 3 uses of RADIO waves.
- Television
- Radio
- Telecommunications
What is the range of Wavelength (m) of MICROWAVES?
What is its range of Frequency (Hz)?
10^-4 - 10 ^-1 m
3 x 10^12 - 3 x 10^9 Hz
Give 4 uses of MICROWAVES.
- Radar
- Mobile Phones
- Microwave Ovens
- Satellite Navigation
What is the range of Wavelength (m) of INFRA-RED?
What is its range of Frequency (Hz)?
7.4 x 10^-7 - 10^-3 m
4 x 10^14 - 3 x 10^11 Hz
Give 3 uses of INFRA-RED.
- Heaters
- Night-Vision Equipment
- Remote Controls
What is the range of Wavelength (m) of VISIBLE LIGHT?
What is its range of Frequency (Hz)?
3.7 x 10^-7 - 7.4x10^-7 m
8x10^14 - 4 x 10^14 Hz
Give 2 uses of VISIBLE LIGHT.
- Sight
2. Communication
What is the range of Wavelength (m) of ULTRAVIOLET?
What is its range of Frequency (Hz)?
10^-9 - 3.7x10^-7 m
3x10^17 - 8x10^14 Hz
Give 4 uses of ULTRAVIOLET.
- Disco lights
- Tanning studios
- Counterfeit detection
- By detergents
What is the range of Wavelength (m) of X-RAYS?
What is its range of Frequency (Hz)?
10^-12 - 10^-7 m
3x10^20 - 3x10^15 Hz
Give 3 uses of X-Rays.
- Computer-aided tomography (CT) scans
- X-Ray Photography
- Crystal Structure Analysis
What is the range of Wavelength (m) of GAMMA RAYS?
What is its range of Frequency (Hz)?
10^-16 - 10^-9 m
3x10^24 - 3x10^17 Hz
Give 2 uses of Gamma Rays.
- DIAGNOSIS and CANCER treatment (radiotherapy)
2. STERILISING EQUIPMENT
