T6 electromagnetic waves Flashcards
what type of spectrum do electromagnetic waves form
continuous spectrum
what type of spectrum do electromagnetic waves form
continuous spectrum
order the types of electromagnetic radiation from lowest to highest frequency
radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays
how do the speeds of EM radiation differ in a vacuum and in air
electromagnetic waves all travel at the same speed in a vacuum and in air
what property of waves in different mediums causes refraction
- velocity
- wave speed is slower in denser materials, causing refraction
in which direction do waves refract when entering a denser medium
- bend towards the normal
- angle of refraction is less than the angle of incidence
what type of waves can be produced by oscillations in an electrical circuit
radio waves
how can radio waves create an alternating current in a circuit
when radio waves are absorbed, they can induce oscillations in a circuit with the same frequency as the waves themselves
where do gamma rays originate from
changes in the nuclei of atoms
what health effects can ultraviolet waves cause
- can cause the skin to age prematurely
- can increase the risk of developing skin cancer
what health effects can X-rays and gamma rays cause
- ionising radiation so can cause mutations in genes
- can lead to increased risk of developing various cancers
give 3 practical uses for infrared radiation
- electrical heaters
- cooking food
- infrared cameras
give 2 practical uses for microwave radiation
cooking food
satellite communications
give 2 practical uses for radio waves
television transmission
radio transmission
what wave phenomenon is used by lenses to form an image
refraction
how does a convex lens form an image
parallel rays are refracted and brought together at a point known as the principal focus
what is meant by the focal length of a lens
distance from the lens to the principle focus
what is the difference between the image produced by a convex and a concave lens
- convex lenses can produce real or virtual images
- concave lenses can only produce virtual images
why does magnification not have a unit
- it’s the ratio between image height and object height
- ratios don’t require units
symbol used to represent a convex lens in a ray diagram
symbol used to represent a concave lens in a ray diagram
>
what determines the colour of visible light waves
wavelength and frequency of the light waves
what colour of visible light has the highest frequency
blue
what colour of visible light has the largest wavelength
red
