What is light made up of?
Electromagnetic radiation with a magnetic field and an electric field travelling at 90 degrees to each other, both following a sinusoidal pattern.
If light has a high frequency, what colour would it be?
Blue
What type of light exists outside of the range visible to humans?
At high frequencies, ultraviolet
At low frequencies, infrared
Light range visible to humans
400 nm (blue) to 700 nm (red)
Speed of light in a vacuum
300 000 000 metres per second
Difference between reflection and refraction
Reflection: Wave bounces back when it hits a different medium
Refraction: Change in direction when light enters a medium
Characteristics of the image formed in a plane mirror
Same size, virtual and laterally inverted
Two types of images generated by a mirror or lens
Real and virtual
Real can be projected onto a screen or wall
Virtual can only be seen by looking into the optics
Convex mirror
Diminishes the image and provides a wider field of view
Concave mirror
Curves inwards
Close to mirror: Magnified, upright and virtual
Far from mirror: Diminished, inverted and real
How to work out the refractive index of a material?
Speed of light in vacuum / speed of light in material
What is the angle of reflection when light is reflected on a plane?
Equal to the angle of incidence. The incident ray, reflected ray and plane normal all lie on the same plane
In which case of refraction does the light change speed but not direction?
When the light ray passes perpendicular to the boundary between the two boundaries
What is a lens?
An optical device that refracts light
Snells law?
Sin θ1/Sin θ2=n2/n1=V 1/V 2
What is the difference between a lens and a mirror
A lens forms an image by refraction whereas a mirror forms an image by reflection
How does light behave when travelling from air into glass and vice versa?
Air to glass: Rays refracted towards the normal
Glass to air: Rays refracted away from the normal
Characteristics of a convex lens
Thicker at the centre than at the edges
Image may be real or virtual depending on position of object and observer
Characteristics of a concave lens
Thinner at its centre
Image formed is always upright, virtual and diminished
Which type of lens is used to magnify an image?
Convex lens
Advantages of fibre optic
Lighter and smaller
Able to carry more information
Intrinsically safer (does not pose fire risk)
Disadvantages of fibre optic
Difficult to terminate, difficult to repair
How can wavelengths invisible to the human eye be detected?
Using instruments such as X-Rays
How can the speed of light be calculated?
Wavelength X Frequency
