Paper 2 Lenses/light Flashcards
What are the two major types of lens
Concave (or diverging)
Convex (or converging)
What is a converging lens
The lens is thicker at the centre than it is at the edges
It makes parallel rays of light converge to a single point, F (this point is the principle focus of the lens)
What is the focal length
The distance between the focus point and the centre of the lens
What is a diverging lens
The lens in thinner at its centre than at its edges
Makes parallel rays of light diverge as though from a single point, F
Magnification =
Image height/ object height
If the image is larger than the object the magnification is…
Greater than 1
If the image is smaller than the object the magnification is…
Less than 1
What are ray diagrams used for
Used to explain the formation of the image
Two rays of light which originate from a single point on the object should be drawn
The image produced from a convex lens can be
Diminished/magnified
Inverted/upright
Real/virtual
What happens in ray diagrams for concave lenses
The ray parallel to the principal axis will reflect as if it passes through the focal point on the objects side
What is white light made up of
All the wavelengths in the visible part of the spectrum
How are the colours of the spectrum separated
The different wavelengths experience different changes in speed as they enter and leave the glass so bend (refract) by different amounts, so the colours are separated
Cyan is made by mixing…
Green and blue
Magenta is made by mixing…
Red and blue
Yellow is made by mixing…
Red and green
