Light And The Electromagetic Spectrum Flashcards
What is the behaviour of light when it is refracted through a glass block?
It bends towards the normal as it enters the glass and away from the normal as it leaves the glass.
Rays of light that meet the glass at 90 degrees continue without a change in direction
State the law of reflection
The angle of incidence is equal to the angle of reflection
Describe the differences between specular reflection and diffuse reflection
Specular reflection occurs when parallel rays of light are reflected off a smooth surface
Diffuse reflection occurs when light rays are reflected at many different angles on a rough surface (eg. a painted wall)/
What do filters do?
How would a green filter work?
Filters let through different colours of light and absorb all other colours.
A green filter would let through or ‘transmit’ green and absorb all the other wavelengths
What are lenses?
Pieces of glass that bend light using refraction to bring it into focus
What does a converging lens do?
How do you increase the power of a converging lens?
Bends rays of light towards one another, bringing them to a point.
By making it fatter so it has more sharply curved faces - resulting in a shorter focal length
How do we know that an image is real? (Not virtual?)
The rays meet at a point and the image can be produced on a screen.
In virtual images, the rays diverge
What are three properties of electromagnetic waves?
Transverse waves, travel at the same speed in a vacuum, transfer energy to the observer
What is the relationship between the frequency and the wavelengths in the electromagnetic spectrum?
As the frequency of the radiation increases, the wavelength decreases
List the main groups of electromagnetic waves from longest to shortest wavelength
Radio, microwave, infrared, visible, ultraviolet, x-ray, gamma
Why can’t we get a suntan if we are inside the house?
The ultraviolet rays that cause suntans aren’t transmitted through the walls of the house, they are absorbed
How does radiation cause a body’s temperature to increase?
If it absorbs more radiation than it emits
Why are gamma rays and x-rays the most dangerous?
Because they have the highest frequencies and lowest wavelengths.
They can cause mutation to DNA, which can cause cancer
What are the uses of gamma rays?
To sterilise food and detect and treat cancer
What are the uses and dangers of ultraviolet light?
Uses include disinfecting water.
Damaged skin cells, causing sunburn and can lead to skin cancer
