P1.5 EM Spectrum and Soud Flashcards
What do waves do?
All waves move energy from one place to another and can be either;
transverse
or
longitudinal.
Define longitudinal waves.
Particles move in same direction as movement of wave have compression’s and rarefractions.
Define transverse waves.
Particles move 90 degrees to direction of wave and have peaks and troughs.
What 2 things do electromagnetic waves have in common?
Electromagnetic waves are transverse and travel at the same speed through a vacuum 300,000km/s.
State the order of the electromagnetic spectrum.
Gamma rays. X-rays. Ultraviolet rays. Visible light. Infra-red rays. Microwaves. Radiowaves.
Are mobile phones harmful to some users?
There is some evidence to support that mobile phones are harmful so some users.
However, there is evidence to support the contrary.
What is a use for radio waves, microwaves, infra-red and visible light?
Can be used for communication.
How do we communicate with satellites?
Microwaves can pass through the Earth’s atmosphere.
Radio waves cannot.
How are electromagnetic waves used in optical fibres?
Infra-red and visible light can be used to send signals along optical fibres and so travel in curved paths.
What is the ‘normal’ line?
The ‘normal’ is a line 90 degrees to the mirror at the point of reflection.
What is the law of reflection?
The angle of incidence is equal to the angle of reflection.
How do we describe the image produced in a plane mirror?
The image produced in a plane mirror is virtual, upright and laterally inverted.
Explain what happens during refraction.
Wave-fronts change direction when they enter a material at an angle and move at a different speed.
Explain what happens during diffraction.
Waves spread out when they come to an edge or a gap.
Diffraction happens more if the gap is the same size as the wavelength of the wave.
Define frequency.
A number of waves passing a point per second.
