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Flashcards in Lenses Deck (23)
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1
Q

How do lenses form images

A

By refracting light and changing its direction

2
Q

What are the main 2 types of lenses

A

Convex

Concave

3
Q

What happens to a convex lens and what does it do to light

A

It bulges outward

Causes rays of light parallel to axis to be brought together at the principle focus

4
Q

What do concave lenses do and what do they do to light rays

A

The lens caves inwards

Causes rays of light parallel to axis to spread out

5
Q

What is the axis of a lens

A

A line passing through the middle of the lens

6
Q

What is the principal focus of a
Convex lens
Concave lens

A

Convex - rays hitting the lens parallel to axis all meet

Concave - point where rays hitting the lens parallel to axis appear to all come from

7
Q

What is the focal length

A

The distance form the centre of the lens to the principal focus

8
Q

What are the 3 rules of refraction in a convex lens

A

Incident ray parrallel to axis refracts through lens and passes through principal focus on otherside
Incident ray passing though the principal focus refracts though lens and travels parallel to axis
Incident ray passing though centre of lens carries on in same direction

9
Q

What are the 3 rules for refraction in concave lens

A

Incident ray parallel to axis refracts through lens and travels in line with principal focus
Incident ray passing through the lens towards the principal focus refracts through lens and travels parallel to axis
Incident ray passing though centre carries on in the same direction

10
Q

What is a real image

A

Where the light from the object comes together to form an image on a screen

11
Q

What is a virtual image

A

The rays are diverging so the light from the object seems to be coming from a completely different place

12
Q

When do you get virtual images

A

When looking in mirror

Magnifying lens

13
Q

How do you describe an object

A

How big it it
If it’s upright or inverted relative to object
Real or virtual

14
Q

What type of image does a concave lens always produce

A

A virtual image

That is upright, smaller and on the same side of lens as the object

15
Q

How do magnifying glasses work

A

They create a magnified virtual image

16
Q

What can’t you do with a virtual image

A

You can’t project a virtual image into a screen because the light rays don’t actually come from the place where the image appears to be

17
Q

What is the magnification Formula

A

Image height / object height

18
Q

What is the range of wavelengths in visible light

A

400-700 nm

19
Q

What are opaque objects and what colour are they

A

They do not transmit light
They absorb some wavelengths of light and reflect others
It’s colour depends on which wavelengths of light are most strongly reflected

20
Q

What do opaque objects that aren’t a primary colour reflect

A

Wavelengths of light corresponding to that colour
Or
Wavelengths of the primary colours that can mix tougher to make that colour

21
Q

What do transparent and translucent objects do with light

A

They transmit light so it can pass through

22
Q

What are colour filters

A

They are used to filter out different wavelengths of light so that only certain colours are transmitted and the rest are absorbed

23
Q

What happens if you look at a red hat through a blue colour filter

A

The hat would appear black because red light is relegated by the hat but it’s not transmitted because the only colour that would be transmiteed would be a
Blue coloured hat