Prisms Flashcards

1
Q

Prism?

A

Two flat polished refracting surfaces inclined at an angle relative to each other

Prisms have an apex, apex angle, base

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2
Q

What does dispersion mean?

A

When a beam of light passes through a prism it splits into a spectrum of colours

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3
Q

Why is blue light refracted more than red light?

A

Blue is shorter in wavelength

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4
Q

Dispersion can not occur for what light?

A

Monochromatic light

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5
Q

Where does the light move towards?

A

The base

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6
Q

Where does the image move towards

A

The apex

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7
Q

What is the angle of deviation dependant on

A

-refractive index of prism
-angle of incidence
-apex angle

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8
Q

What is the angle of deviation

A

The light ray is deviated towards the base of the prism, this net change in direction is called the angle of deviation

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9
Q

What is the minimum angle of deviation

A

It occurs when the light passes symmetrically through the prism, the angle of incidence equals the angle of emergence

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10
Q

What are the unit for prisms

A

Prism dioptre
Centrad

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11
Q

Where does displacement happen for a prism diaptore

A

Over a flat surface

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12
Q

Displacement for centrad?

A

Over an arc

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13
Q

Prism power?

A

How much the prism causes the light to change direction

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14
Q

Prism dioptre formula

A

P= shift in cm/ distance in m

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15
Q

Prisms at more powerful in what position?

A

Prentice position than in the position of minimum deviation

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16
Q

Prentice position?

A

90 degrees to the interface and straight

17
Q

Using mostly thin prisms leads to?

A

Good quality images, this is shifted but not deformed because of the small apical angle of the prism

Small apical angle= good image quality

18
Q

What is a Lens

A

A lens is an optical device used to alter the vergence of light passing through it

19
Q

What is the formula for vergence power or surface power

A

F = n2-n1 /r

If F IS POSITIVE than it’s converging- moving towards axis
IF F IS NEGATIVE THAN it’s diverging

F IS MEASURED IN D (diopters) not that same as prims diopters

20
Q

How do you identify a convex lens

A

It’s thicker in the centre and thinner edge

Other forms of convex lenses are biconves lens, plano convex and convex meniscus which all have a positive vergence power

21
Q

How to you identify concave lenses

A

Thin centre and thicker edge

Examples are biconcave lens, plano concave and concave meniscus which all have a negative vergence power

22
Q

Thins Lens?

A

Thickness can be ignored so bending of light rays takes place approx at the centre of Lens

23
Q

How many focal points do lens have

24
Q

How many focal points do mirrors have

25
For a convex lens where is F2 located
Behind the lens
26
For a convex lens, where is F1 located
Infront of the lens
27
For concave lens where is F2 located
Infront of the lens- this is where parallel rays cross
28
For concave Lens where is F1 located
Behind the lens so rays from F1 are deflected into parallel rays
29
What is the vergence power related to
The focal point - the shorter the focal length the more powerful the lens
30
The vergence power is related to the focal point What is the formula to calculate the focal length?
F= 1/ f(in metres)