physics paper 2 Flashcards
When can refraction happen?
When any wave changes speed as it passes from one medium to another
What happens if the waves enter or leave the medium at right angles to the surface?
They do not change direction
What are wavefronts and why are they useful?
An imaginary line that connects all the same points in a set of waves and it makes it easier to visualise lots of waves moving together
What is refraction?
When a wave changes speed or direction because they huge entered a different medium
What are electromagnetic waves also known as?
Transverse waves because they transfer energy from the source of waves to an absorber
Example of electromagnetic wave?
Microwaves because they transfer energy from the oven to the food
What are light waves?
Transfer energy from the sun to the absorber
Where’s red on the spectrum?
Has lowest frequency but longest wavelength
Where’s violet on the spectrum?
Has highest frequency but shortest wavelength
What’s the electromagnetic spectrum?
Radio
Microwaves
Infrared
Visible light
Ultraviolet
X-Rays
Gamma rays
What is a vacuum?
What electromagnetic waves travel through and they all travel at the same speed
What is an oscillations?
When the wave is moving up and down
What are transverse waves?
When the oscillations are perpendicular to the direction of the energy transfer and they require a medium to travel in
What are longitudinal waves?
When the oscillations are parallel to the direction of energy transfer
What is a period and how do you figure it out?
The time for one wave to pass a point
Period (s) = 1/frequency (Hz)
What is frequency?
The number of waves passing a point each second
What is wave speed?
The speed at which the wave moves through the medium
How do you figure out wave speed?
Wave speed= frequency x wavelength
What happens when electromagnetic waves are generated or absorbed?
Changes take place in atoms or in the nuclei of atoms
Risk of X-Rays and gamma rays?
Risk of cancer as they cause the mutation of genes but can be used in medical treatment
What’s the dose of radiation measured in?
Sieverts (Sv) or millisieverts (mSv)
Why are radio waves used in radios or TV signals?
Because they can travel long distances before being absorbed
Why are microwaves used to communicate with satellites in space?
Because they can pass through the Earths atmosphere without being reflected or refracted