P14 - Light Flashcards
What is the angle of incidence?
The angle between the incident ray and the normal
What is the angle of reflection?
Angle between the reflected ray and the normal
What is a concave lens?
A lens that makes parallel rays diverge (spread out)
What is a convex lens?
A lens that makes light rays parallel to the principal axis converge (meet) at a point
What is diffuse reflection?
Reflection from a rough surface - the light rays are scattered in different directions
What is the focal length?
The distance from the centre of the lens to the point where light rays parallel to the principal axis are focused
What is magnification?
image height / object height
What is a magnifying glass?
A converging lens used to magnify a small object which must be placed between the lens and its focal point
What is the normal?
A straight line through a surface or boundary perpendicular to the surface or boundary
What is an opaque object?
An object which light cannot pass through, instead the object absorbs or reflects the light
What is the principal focus?
The point where light rays parallel to the principal axis of a lens are focused for a convex lens, and where the light rays appear to originate from for a concave lens
What is a real image?
An image formed by a lens that can be projected onto a screen
What is refraction?
The change of direction of a light ray as it passes across a boundary between 2 transparent substances
What is specular reflection?
Reflection from a smooth surface. Each light ray is reflected in a single direction
What is a translucent object?
An object that allows light to pass through, but the light is scattered or refracted as it does so, due to lots of internal boundaries in the object
What is a transparent object?
An object that transmits all the incident light that enters the object
What is a virtual image?
An image, seen in a lens or a mirror, from which light rays appear to come after being refracted by a lens or reflected by a mirror. They cannot be projected onto a screen
When would sound be relfected?
In an echo
What is the law of reflection?
The angle of incidence = the angle of reflection
What is reflection on a smooth surface known as and why?
Specular reflection, this is because parallel light rays are reflected in a single direction, they are not scattered. Each of the incident angles are the same, therefore each of the angles of reflection are the same
What is reflection on a rough surface known as and why?
diffuse reflection, this is because parallel light rays reflected from a rough surface are scattered in different directions. Each of the incident angles are different, therefore each of the angles of reflection are different
What happens to the velocity of a wave as it travels from an optically rare medium to an optically dense medium?
decreases
What happens to the wavelength of a wave as it travels from an optically rare medium to an optically dense medium?
Decreases
What happens to the frequency of a wave as it travels from an optically rare medium to an optically dense medium?
does not change
What happens to the direction of a wave as it travels from an optically rare medium to an optically dense medium?
bends towards the normal
What happens to the velocity of a wave as it travels from an optically dense medium to an optically rare medium?
increases
What happens to the wavelength of a wave as it travels from an optically dense medium to an optically rare medium?
increase
What happens to the frequency of a wave as it travels from an optically dense medium to an optically rare medium?
Does not change
What happens to the direction of a wave as it travels from an optically dense medium to an optically rare medium?
bends away from the normal
What causes refraction?
Waves change speed as they pass between substances of different densities, this causes them to change direction