Flashcards in Lenses Deck (8)
What is refraction and how does a lens form an image?
the change in direction of light as it passes from one medium to another
forms an image by refracting light
What happens to light as it passes through a converging lens?
a converging lens is curved outwards
rays from a single point on a distant object arrive at the lens parallel to one another
the lens refract the parallel rays together at a point called the principal focus
What happens to light as it passes through a diverging lens?
curved inwards at both sides
refract the parallel rays of light so they spread apart
forms a virtual image - light rays appear to come from from a point but don't actually
appear to come from a different point to where the object is
the point where the object appears to come from is the principal focus
What is focal length?
in converging lenses:
-distance between the centre of the lens and the image
in diverging lenses:
-distance between the centre of the lens and the virtual image
What can an image be?
real or virtual
upright or inverted
enlarged or diminished
How do magnifying glasses work?
if the object is placed between the principal focus and a converging lens the image will produce an enlarged, upright and virtual image
What is the nature of images from converging lenses?
when the object is further than 2F, it is diminished, inverted, real and between 2F F
when the object is 2F, it is the same size, inverted, real and the position is 2F
between 2F and F, magnified, inverted, real and further 2F
2F - no image because the emerging rays are parallel to the axis
when it is closer than F, it is magnified, upright and virtual, it is on the same side as the object