Energy Transmission and Electromagnetic Radiation Flashcards
What is light?
A form of energy that travels in the form of oscillating electric and magnetic fields.
Travels fastest in a vacuum (3x10^8 m/s))
What is the law of reflection?
i = r
on a flat surface, the incident ray is equivalent to the reflected ray.
What is refraction?
The change of direction when light passes from one medium to another.
How does the refractive index of a substance affect the speed of light?
The higher the refractive index, the slower light travels. eg air: 1, water: 1.33
If the light travels slower, it bends towards the normal, and away if it is travelling faster.
What is total internal reflection?
Total internal reflection occurs when the angle that light approaches a less dense medium is greater than the critical angle, and the light reflects instead of passing through.
What are convex lenses?
Convex lenses converge parallel rays of light to a real focal point on the principal axis. The flatter the lens, the longer the focal length.
They can produce real images if the object is further away than the focal point.
What are concave lenses?
Concave lenses diverge straight beams of light away from the principal axis. They have a virtual focal point, and can only form virtual images.
What is the focal length?
The distance between the centre of the lens to where the light rays meet
What is the difference between transverse and longitudinal waves?
In transverse waves, the medium travels perpendicular to the direction of the waves, whereas in longitudinal waves, the medium travels parallel to the direction of the wave.
In both waves, matter is not transferred: only energy.
What is amplitude in a transverse wave?
Amplitude is the maximum distance the wave extends from the middle point.
Units: m
symbol: a
What is wavelength in a transverse wave?
The distance between two successive peaks.
Units: m
symbol: lambda
What is frequency?
The number of oscillations per second.
Unit: hz
symbol: f
What is the formula for the speed of a wave?
speed = frequency x wavelength v = f x lambda
What are the properties of light?
Any electromagnetic wave (visible or not)
It does not need a medium to travel through
It can be reflected, transmitted or absorbed by a surface
What colour do objects appear under a primary coloured light?
Object under a primary coloured light can either look the colour or black. White and the colour appear that colour and so do the secondary colours that it produces.
