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Flashcards in Lenses Deck (8)
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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


What are the nature of images produced from diverging lenses?

always produced images that are virtual, upright and diminished

the image always appears to come from the same side of the lens as the object

in a ray diagram the lines must be traced backwards, until they reach a point where they cross