P14(Light) Flashcards
What is the normal
The line perpendicular to the mirror
What is the angle of incidence
The angle between the incident ray and the normal
What is the angle of reflection
The angle between the reflected ray and the normal
What is the law of reflection
The angle of incidence = the angle of reflection
What is a virtual image
An image that is formed when the light rays from an object do not meet but appear to meet behind the lens
What is specular reflection
-Reflection from a smooth surface in a single direction
-the angle of reflection is equal to the angle of incidence
What is diffuse reflection
Reflection from a rough surface causes scattering
What is refraction
The change in direction of waves when they travel across a boundary from one medium to another
When a light ray refracts from air into glass …
The angle of refraction is less than the angle of incidence
When a light ray refracts from glass into air
The angle of refraction is more the angle of incidence
The wavelength of light increases….
From violent to red across the visible spectrum
The colour of a surface depends on …
The pigments of the surface materials and the wavelengths of light the pigments absorb
What is a translucent object
-An object that lets light pass through it
-but scatters the light inside it
What is a transparent object
-An object that lets all the light that enters it through it
-does not scatter the light inside the object
What is a convex lens
A lens that focuses parallel rays to a point called the principal focus
What is the principal focus
The point where parallel rays are focused to
What are convex lens used for
-magnifying glass
-camera
What is a concave lens
A lens that makes parallel rays spread out as if they had come from the principal focus
What is a concave lens used for
To correct short sight
What is the focal length
The distance from the centre of the lens to the principal focus
A real image is formed…
if the object is placed at a distance greater than the focal length from the lens
A virtual image is formed…
If the object is placed closer to the lens than the focal length
What’s the formula for magnification
When an object is placed between a convex lens and its principal focus …
The image formed is virtual
What is the lens diagram for a convex lens for a real image
How would you describe a real image on a convex lens diagram
Real: the light rays meet each other after refraction
Magnified: the image is larger than the object
Inverted: the image is formed on the opposite side of the principal axis
What is the lens diagram for a convex lens for a virtual image
How would you describe a virtual image on a convex lens diagram
Virtual: the light rays appear to meet when produced backwards
Magnified: the image is larger than the object
Upright: the image is formed on the same side of the principal axis
Concave lens only produce …
Virtual images
What is the lens diagram for a concave lens
How would you describe an image on a concave lens diagram
Virtual: the light rays appear to meet when produced backwards
Diminished: the image is smaller than the object
Upright: the image is formed on the same side of the principal axis
What is a real image
An image that is formed when the light rays from an object converge and meet each other
Real images are always ….
inverted
Virtual images are always ….
upright
What is the visible spectrum
Colour filters work by …
-absorbing certain wavelengths and transmitting other wavelengths
-For example, when white light passes through a red filter:
Red light is transmitted
All the other colours are absorbed
An object will appear white if …
All wavelengths are reflected equally
An object will appear black if …
All wavelengths are absorbed
An object will appear transparent if …
All the light is transmitted, and only a small amount is reflected or absorbed
