Lenses Flashcards

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1
Q

What is a lens?

A

Shaped piece of transparent glass or plastic that reflects light

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2
Q

What happens when light is refracted?

A

It changes direction due to the change in density as it moves from air to glass or plastic

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3
Q

Where are lenses used?

A

Cameras
Telescopes
Binoculars
Microscopes
Corrective glasses

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4
Q

What does a concave lens look like?

A

Thinner in the middle then the edges

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5
Q

What do light rays do in convex lenses?

A

Parallel light rays enter the lens and converge
They come together at a point called the principle focus

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6
Q

How are convex lenses drawn in ray diagrams?

A

They are drawn as a vertical line with outwards facing arrows to indicate shape of the lens

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7
Q

What is focal length ?

A

Distance from lens to principle focus

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8
Q

What do concave lenses look like?

A

Thinner in the middle than the edges

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9
Q

What happens to light rays in a concave lens?

A

Parallel rays diverge
They separate but appear to come from behind a principle focus on the other side of the lens

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10
Q

How are concave lenses drawn in ray diagrams?

A

It’s drawn as a vertical line with inwards facing arrows to indicate shape of the lens

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11
Q

What can images formed by a lens be?

A

Upright or inverted
Magnified or diminished
Real or virtual

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12
Q

What is a real image?

A

Image that can be projected onto a screen

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13
Q

What is a virtual image?

A

Image appears to come from behind the lens

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14
Q

What are light rays in virtual images like?

A

Rays of light appear to come but do not so in reality

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15
Q

What devices contain convex lenses?

A

Cameras and eyes

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16
Q

What does the image formed by a convex lens depend on?

A

Lens used
Distance from object to lens

17
Q

What type of image is formed when the object is placed far from the lens?

A

Inverted
Diminished
Real

18
Q

How must film be loaded into a projector?

A

Upside down so the projected image is the right way up

19
Q

How do convex lenses make an object appear larger than it actually is?

A

Object is placed at a distance less than the focal length

20
Q

What is the image of magnifying glasses like:

A

Upright
Magnified
Virtual

21
Q

Why can’t a magnifying glass be projected onto a screen?

A

Because it is a virtual image

22
Q

What happens to light rays in concave lenses in peep holes?

A

They will be referacted and diverge on the other side of the lens

23
Q

How do concave light rays appear?

A

From the same side as the principle axis so the image will be upright
Further from the principle axis so the image will be smaller than the object

24
Q

What image do concave lenses produce?

A

Upright
Diminished
Virtual

25
Q

What is the order of visible light frequency

A

Red
Orange
Yellow
Green
Blue
Indigo
Violet

26
Q

Where can waves be absorbed?

A

At the boundary between two different materials

27
Q

What happens when waves are absorbed by a surface?

A

The energy of the waves is transferred to the particles in the surface
This increases the internal energy of the particles

28
Q

What happens when white light is shined on an opaque object?

A

Some of the wavelength or colours are absorbed and not detected by our eyes
Other wavelengths are reflected and detected by our eyes

29
Q

How does grass appear green?

A

Red,orange,yellow,blue,indigo,violet are absorbed the the grass
Green is reflected by the grass and detected by our eyes

30
Q

Where can waves be transmitted?

A

At the boundary between two different materials

31
Q

Why do waves continue transmitting through air,glass and water?

A

Because they are good at transmitting light
They are transmitted with very little absorption

32
Q

What are translucent materials

A

Materials that transmit some light but not completely clear

33
Q

What are examples of translucent objects?

A

Lamp shades
Shower curtains
Window blinds

34
Q

What happens when light passes through a colour filter?

A

All colours are absorbed except the colour of the filter

35
Q

What makes an object appear black?

A

If the object absorbs all of the wavelength of visible light

36
Q

What happens to a blue object placed in red lighting?

A

It appears black because there is no blue light to reflect