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Physics - Paper 2 > P5.3 > Flashcards

P5.3 Flashcards

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1
Q

What do lenses do

A

refract light passing through them.

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2
Q

What is the principle focus

A

The point where lights parallel rays meet or appear to meet.

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3
Q

What is the focal length

A

The distance from the lens to the principal focus.

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4
Q

The shorter the focal length….

A

the more powerful the lens.(because it has refracted the light rays more)

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5
Q

What are convex lenses

A

Makes parallel rays passing through itconverge (focus) to a point.

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6
Q

Uses of convex lenses

A
  • magnifying lenses

- correcting long - sight

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7
Q

What is a concave lens

A

Makes parallel rays passing through it diverge (spread out).

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8
Q

Uses of concave lenses

A
  • correcting short-sightedness
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9
Q

How do rays from nearby objects appear

A

Rays from nearby objects appear to travel diverging from each other

Lens is thick, refracts light rays a lot to bring to focus.

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10
Q

How do rays from distant objects appear to be travelling

A

Rays from distant objects appear to travel parallel to each other

Lens is thin, refracts light rays a little to bring to focus.

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11
Q

Causes of Short sightedness

A

Lens is too thick… too powerful… refracts light rays too much… rays come to a focus in front of retina

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12
Q

How do concave lenses fix shirt sightedness

A

Concave lens diverges rays before they enter eye

A concave lens is used to diverge parallel light rays before they enter the eye.

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13
Q

Causes of long - sightedness

A

Lens is too thin… too weak… refracts light rays a little… rays come to a focus behind retina

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14
Q

How to convex lenses fix long sightedness

A

A convex lens is used to converge diverging light rays before they enter the eye.

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15
Q

What is a real image

A

Image that is formed where light rays meet.

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16
Q

What is a virtual image

A

Image that is formed where light rays appear to come from.

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17
Q

Which lenses produce real images

A

object is OUTSIDE the focal length of a converging lens

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18
Q

Which lenses produce virtual image

A

object is INSIDE the focal length of a converging lens

formed by a diverging lens

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19
Q

What is an upright image

A

Image is same way up as object.

20
Q

What is an inverted image

A

Image is upside down compared to object.

21
Q

Which lenses produce magnified images

A

Images appear magnified when an object is placed INSIDE the focal length of a CONVERGING lens.

22
Q

Equation for magnification

A

Magnification = image height / object height

23
Q

Draw a convex lens, with the image OUTSIDE the focal point

A
24
Q

What type of image is produced in a convex lens, with the image OUTSIDE the focal point

A

Image is…
Real
Inverted
Diminished

25
Q

Draw a convex lens, with the object INSIDE focal point

A
26
Q

What type of image is formed from a convex lens, with the object INSIDE focal point

A

Image is…
Virtual
Upright
Magnified

27
Q

Draw a concave lens diagram with the object OUTSIDE focal point

A
28
Q

What type of images do concave/ diverging lens form

A

All diverging lens form the same image…

VirtualUpright
Diminished

29
Q

How to figure out if an image is magnified or diminished from a lens diagram

A

If the image height is higher then the actual object = magnified

If the image height is lower then the actual object = diminished

30
Q

Why do thicker lenses have shorter focal lengths

A

Because light spends more time travelling through the thicker Lens so it will end up being bent more

31
Q

If a concave lens diverges more, how does that effect focal length

A

Shorter focal length

32
Q

If a convex lens converges more, how does that effect focal length

A

Shorter focal length

33
Q

What is dispersion

A

Dispersion is the splitting of white light into its constituent wavelengths (spectrum).

34
Q

Why does light disperse

A

Different wavelengths of EM radiation travel at different speeds within glass, so refract by different amounts.

35
Q

How does wavelength effect refraction

A

Smaller the wavelength, the more the refraction.

36
Q

Which refracts more blue or red

A

Blue

37
Q

What does it mean if someone sees an object as blue under white light

A

If an object appears a certain colour under white light (e.g. blue), it is reflecting only that frequency (blue) and absorbing all the other frequencies (red, green, yellow etc.)

IT IS REFLECTING BLUE + ABSORBING ALL OTHER FREQUENCIES

38
Q

What does specular reflection produce

A

sharp images(e.g. mirror)

39
Q

What does diffuse scattering produce

A

no images(e.g. sheet of paper)

40
Q

Define a filter

A

Filters absorb certain frequencies of light but transmit others.

41
Q

What does a red filter do

A

will transmit only red light

42
Q

Are transparent coloured objects filters?

A

Yes

43
Q

Polly is wearing a red t-shirt. Jack is wearing a yellow t-shirt.

What colours would their t-shirts appear in…
In red light?
In yellow light?
In blue light?

A

Red light - polly RED and jack BLACK

Yellow light - polly BLACK and jack YELLOW

Blue light - polly BLACK and Jack BLACK

44
Q
A

Blue balloons reflect blue wavelengths of light, under white light.

Red light contains only red light wavelengths.

Thus, when illuminated by red light, the blue balloon will absorb the red light and reflect nothing, appearing black.

45
Q

Suggest why you do not see a spectrum, when white light goes through rectangular glass block

A

A rectangular block has two lines of symmetry.

Thus, the final refracted beam travels parallel to the original incident beam.

Therefore, the different wavelengths of light within white light, aren’t separated out.

46
Q

Shape of concave lens

A
47
Q

Shape of convex lens

A

Physics - Paper 2 (10 decks)

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