3.1-3.23 Flashcards
Transverse Wave
Wave vibrates (oscilates) at right angles to the direction it is travelling
Longitudinal Wave
Wave vibrates (oscilates) are along the same direction as the energy wave is moving
Wavefront
Created by overlapping lots of different waves. A wavefront is where all the vibrations are in phase and the same distance from the source
Amplitude
The distance from their equilibrium position to the peak
Wavelength
The distance between a particular point on one cycle of the wave and the same point on the next cycle
Waves are…
a way of transferring energy from place to place, energy is transfered but matter is not.
Frequency
The number of waves passing a particular point per second. Is measured in Hertz (Hz)
Time period
The time it takes for one complete wave to pass a particular point
wave speed equation
wave speed = freguency x wavelength
v = f × λ
frequency equation
frequency = 1 / time period
Doppler effect
An increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move towards (or away from) each other.
Waves can…
Be reflected and refracted
Electromagnetic spectrum
A continuos spectrum of waves, which includes visible light
radio, microwave, infrared, visible, ultraviolet, x-ray and gamma ray radiations
-All these waves travel at the same speed in free space
Visible light order
Red, orange, yellow, green, blue, indigo, violet
uses of electromagnetic radiations:
radio waves: broadcasting and communications
• microwaves: cooking and satellite transmissions
• infrared: heaters and night vision equipment
• visible light: optical fibres and photography
• ultraviolet: fluorescent lamps
• x-rays: observing the internal structure of objects and materials, including for medical applications
• gamma rays: sterilising food and medical equipment.
detrimental effects of excessive exposure of the human body to electromagnetic waves:
- microwaves: internal heating of body tissue
- infrared: skin burns
- ultraviolet: damage to surface cells and blindness
- gamma rays: cancer, mutation
describe simple protective measures against the risks
wear sun glasses, sun cream and stay in shade for UV
Wear led clothing for Gamma
Light waves…
are transverse waves and that they can be reflected and refracted
Law of reflection
the angle of incidence equals the angle of reflection
Refractive indesx (Snells Law):
n= sin i/ sin r
Total internal reflection is used for…
transmit signals along optical fibres
Critical angle is…
when light passes along the boundary
Critical angle equation
sin C = 1 / n
sound waves are…
longitudinal waves which can be reflected and refracted
practical: investigate the refraction of light, using rectangular blocks, semi-circular blocks and triangular prisms
- Set up your apparatus as shown in the diagram using a rectangular block.
- Shine the light ray through the glass block
- Use crosses to mark the path of the ray.
- Join up crosses with a ruler
- Draw on a normal where the ray enters the glass block
- Measure the angle of incidence and the angle of refraction and add these to your results table
- Comment on how the speed of the light has changed as the light moves between the mediums.
- Repeat this for different angles of incidence and different glass prisms.
practical: investigate the refractive index of glass, using a glass block
- Set up your apparatus as shown in the diagram using a rectangular block.
- Shine the light ray through the glass block
- Use crosses to mark the path of the ray.
- Join up crosses with a ruler
- Draw on a normal where the ray enters the glass block
- Measure the angle of incidence and the angle of refraction and add these to your results table
- Calculate the refractive
index - Repeat steps 2 – 7 using
a different angle of
incidence - Find an average of your
results.
