Light and the electromagnetic spectrum Flashcards
(26 cards)
What is the law of reflection?
angle of incidence = angle of reflection
What is the normal?
An imaginary line that’s perpendicular to the surface at the point of incidence
What is total internal reflection?
When a wave is reflected back into a material
What are the two conditions needed for total internal reflection?
1) The angle of incidence must be greater than the critical angle.
2) The wave must be travelling from a more dense substance into a less dense one.
What happens to a wave at a boundary if the angle of incidence is equal to the critical angle?
It would go along the surface that it hit
What is specular reflection?
When waves are reflected in a single direction by a smooth surface
What is diffuse reflection?
When waves are reflected in all directions by a rough surface
What does the colour of an opaque object depend on?
Which wavelengths of light it reflects
If white, blue and red light through a red filter, how will each colour look?
White > Red
Blue > Black
Red > Red
If the focal length of a lens is shorter, the power of the lens is what?
Greater
If the curvature of a lens increases, what happens to the power of the lens?
It also increases
Understand ray diagrams
Pg 42 in CGP
What does a converging lens look like?
It bulges outwards in the middle
What does a diverging/concave lens look like?
It caves inwards
How does a converging lens affect light rays?
It brings them together at the principal focus
How does a diverging lens affect light rays?
It causes them to spread out
Where is the principal focus of a diverging lens?
Where the rays appear to all come from
What is a real image, can it be captured on a screen and what type of lens is needed to form one?
A real image is formed when the light rays actually come together to form the image. It can be captured on a screen. It is formed by a converging lens.
What is a virtual image, can it be captured on a screen and what type of lens is needed to form one?
A virtual image is when the light rays from the object appear to be coming from a completely different place to where they’re actually coming from. It cannot be captured on a screen. It is formed by a diverging lens.
Are electromagnetic waves transverse or longitudinal?
They are all transverse
When do all electromagnetic waves travel at the same speed?
When they are in a vacuum
All electromagnetic waves transfer energy from a source to an observer, give an example that shows this
When you warm yourself by an electric heater infrared waves transfer thermal energy from the heater (the source) to you (the observer)
Name the 7 main groupings of electromagnetic waves from longest wavelength to shortest
Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays
Name the 7 main colours of the visible light spectrum from longest wavelength to shortest
Red, orange, yellow, green, blue, indigo, violet
