Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PHYSICS FURTHER ADDITIONAL > 3a > Flashcards

3a Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

Name three ways X-rays are used in medicine?

A

Medical diagnosis, CT scans, treat cancer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are X-rays?

A

High frequency, short wavelength EM waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How can X-rays treat cancer?

A

The X-rays are focused on the tumour using a wide beam, this beam is rotated around the patient, this minimises the exposure of normal cells to radiation, and so reduces the chances of damaging the rest of the body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is Ultrasound?

A

Ultrasound is sound with a higher frequency than we can hear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Do Ultrasound waves get reflected at a boundary between media?

A

Partially

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What can you use to find boundaries?

A

Oscilloscope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What formula can you use to work out the distance between the boundaries?

A 
S = V X T 
s= distance in metres, m
v= speed in metres per second, m/s
t= time in seconds, s
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are some uses of ultrasound?

A

Medicine— breaking down kidney stones, pre-natal scanning of a fetus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is refraction caused by?

A

The waves changing speed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a refractive index?

A

The ratio of speed of light in a vacuum to see of light in that medium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How do you work out the refractive index?

A

sin incident ray/ sin refracted ray

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a converging lens?

A

A converging lens is convex- it bulges outwards. It causes parallel rays of light to converge (move together) at the principal focus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a diverging lens?

A

A diverging lens is concave- it caves inwards. It causes parallel rays of light to diverge (spread out)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the axis of a lens?

A

A line passing through the middle of the lens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where is the principal focus of a converging lens?

A

Where rays hitting the lens parallel to the axis all meet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where is the principal focus of a diverging lens?

A

Point where rays hitting the lens parallel to the axis appear to come from

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

DIVERGENT?

A

THEO JAMES

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is focal length?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a real image?

A

Where the light from an object comes together to form an image on a ‘screen’- like the image formed on an eyes retina

20
Q

What is a virtual image?

A

When the rays are diverging, so the light from the object appears to be coming from a completely different place

21
Q

What three things do you need to mention to describe an image properly?

A

1) How big it is compared to the object
2) Whether its upright or inverted relative to the object
3) Whether its real or virtual

22
Q

What type of image does a diverging lens always produce?

A

A virtual image

23
Q

What type of lens does a magnifying glass use?

A

Converging lens (magnified virtual image)

24
Q

What is the magnification formula?

A

Magnification= image height / object height

25
Q

The more powerful the lens, the more what it converges rays of light and therefore the what the focal length?

A

Strongly, shorter

26
Q

What formula do you need to work out the power of a lens?

A

Power(D) = 1/ Focal length

27
Q

What two factors is the focal length of a lens determined by?

A

The refractive index of the lens material, the curvature of the two surfaces of the lens

28
Q

What happens to the power of the lens if the curve becomes more strong?

A

The lens is more powerful

29
Q

What is the cornea?

A

A transparent window with a convex shape and a high refractive index. The cornea does most of the eye’s focusing

30
Q

What is the iris?

A

The coloured part of the eye. Controls the size of the pupil and therefore the intensity of light that enters the eye

31
Q

What is the role of the lens (in an eye)?

A

Focuses light from objects at varying distances

32
Q

What is the image formed on in the eye?

A

The retina

33
Q

How does a camera form images in a similar way to the eye?

A

The image on the film is a real image because light rays actually meet there. The image is smaller that the object, because the objects a lot further way than the focal length of the lens. Film in camera is equiv to the retina in our eye

34
Q

Name two causes of short sight

A

Long eyeball, too powerful cornea or lens

35
Q

Name two causes of long sight

A

Short eyeball, too weak cornea or lens

36
Q

What kind of lens can short sight be corrected with?

A

Diverging- diverges the light before it enters the eye which means the lens can focus it on the retina

37
Q

What kind of lens can long sight be corrected with?

A

Converging- the light is refracted and starts to converge before it enters the eye which means the lens can focus it on the retina

38
Q

How can lasers be used in surgery?

A

To vaporise some of the cornea to change its shape- this changes its focusing ability, can increase or decrease the power of the cornea so that the eye can focus images properly on the retina

39
Q

How can light be sent along optical fibres?

A

Total internal refraction

40
Q

If a wave travels through a dense substance like glass or water towards a less dense substance like air, can total internal refraction take place?

A

Indeedydoody

41
Q

Name two materials X-rays are absorbed by

A

Bones and metal

42
Q

What is a charge-coupled device?

A

A device that detects X-rays ad produces electronic signals which are used to form high resolution images

43
Q

Explain why ultrasound rather than X-rays are used to take images of a foetus

A

X-rays are ionising and therefore can cause cancer, not safe to use on babies

44
Q

What is the critical angle?

A

The smallest angle of incidence for which light is totally reflected

45
Q

A dense material with a high refractive index has a what critical angle?

A

A low critical angle

46
Q

What formula relates refractive index and critical angle (c)?

A

Refractive Index= 1/ sin c

47
Q

What is an endoscope?

A

A thin tube containing optical fibres that lets surgeons examine inside the body

PHYSICS FURTHER ADDITIONAL (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions