P1.8/9 - Electromagnetic waves Flashcards
What do waves do?
All types of waves transfer energy from one place to another.
Waves are made up of a series of __________ or vibrations travelling through space.
oscillations
What is a transverse wave?
A transverse wave is a wave in which the oscillations are always at right angles to the direction of the wave motion.
What is the amplitude of a wave?
The maximum height of the wave measured from the middle. Measured in metres.
What is the wavelength of a wave?
The shortest distance between one point and the same point on the next wave. Measured in metres.
What is the frequency of a wave?
The number of waves passing a point per second (or number of oscillations a second). A frequency of 6 Hz means that 6 waves passes a point every second. Measured in hertz (Hz).
kHz = Kilohertz
MHz = Megahertz
The speed of a wave depends on its frequency and wave length. What calculation can you use to find the speed of a wave?
wave speed (m/s) = frequency (Hz) x wavelength (m) λ= wavelength (Greek letter lam-da) v= wave speed f= frequency
Give three examples of electromagnetic waves
- Light
- Microwaves
- X-rays
If electromagnetic(EM) waves don’t need a medium to travel through, they can travel through a ______, e.g space.
vacuum
How does light and infrared rays reach the Earth from the Sun?
They reach the Earth as they do not need a medium to travel through, which means they can travel through a vacuum (space) towards Earth.
What is the electromagnetic spectrum?
The electromagnetic spectrum is a family that the different types of electromagnetic waves are put into.
List the electromagnetic waves in the EM spectrum from longest to shortest.
(longest) Radio waves, microwaves, infrared rays, visible light, ultraviolet, X-rays and gamma rays (shortest)
How do electromagnetic waves travel? (speed, pattern)
All electromagnetic waves travel at the speed of light (300,000,000 m/s) and they all travel in straight lines despite having different frequencies, wavelengths and amplitudes.
How can you see yourself in a mirror?
When you look in a mirror light waves reflect off of the mirror showing your reflection on it. However, all waves can be reflected not just light waves.
The law of reflection states that the angle of incidence is always (i)_____ to the angle of reflection. Even if the surface is really rough, the (ii)___ angles are still the same.
(i) equal
(ii) two
What is refraction?
Refraction is when waves go from one medium to another and change speed, which causes them to change direction. This is why a pencil can look bent when placed in water. If they wave speeds up it bends away from the normal, if the wave slows down it bends towards the normal.
What is the normal?
The intersecting a given line or surface at right angles.
What is diffraction?
Diffraction is whenever a wave passes through a gap or moves around an obstacle. Whenever a wave goes through a gap (a door for example) or an obstacle it spread out. This is why you can still hear someone talking if they are outside and you are inside.
What problems can be caused by diffraction?
Diffraction can cause problems when using optical instruments like microscopes and telescopes. When light enters the instrument it passes through a small gap and diffracts a little. This can lead to a blurry image or loss of detail.
