Light Flashcards

(67 cards)

1
Q

What is reflection?

A

Bouncing back of light in the same medium

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2
Q

What is the law of reflection

A

The incident ray reflected ray and normal all lies on the same plane.
Angle of incidence= angle of reflection

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3
Q

What are the types of spherical mirrors?

A

Concave mirror - caved part is reflective. Converging
Convex mirror - bulging out reflecting mirror. Diverging

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4
Q

What are the types of image ?

A

Real and inverted image - can be obtained on screen. Formed when light rays actually meet
Virtual and erect image - cannot be obtained on the screen. formed when light rays appear to meet

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5
Q

What is the centre of curvature and radius of curvature

A

It is the centre of the mirror denoted by C.
Radius of curvature is the distance between the centre of curvature and pole denoted by R.

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6
Q

Where is focus and focal length ??

A

It lies between the centre of curvature and pole denoted by F.
Focal length is the distance between focus and pole denoted by f.

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7
Q

What is pole ?

A

It is the centre of the mirror surface

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8
Q

What is the principal axis?

A

An imaginary line passing through C F and P.

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9
Q

What is the relationship between f and R

A

f=R/2

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10
Q

When the incident ray is parallel to the principal axis it passes through …….

A

Focus (F)

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11
Q

When the rays of light come from infinity they are ………..

A

Parallel

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12
Q

If a ray of light passes through focus after reflection then it is ………..

A

Parallel to principal axis

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13
Q

If the incident ray passes through Centre of curvature it ………..

A

Bounces back at the same path forming 0°

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14
Q

When the reflected ray passes through the pole it reflects ………

A

Obliquely angle of incidence= angle of reflection both made by principal axis

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15
Q

Concave mirror
When an object is at infinity ♾️

A

The image formed is highly diminished real and inverted and is formed at focus.

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16
Q

Concave mirror
When an object is kept beyond C

A

The image formed is real and inverted between C and F and smaller / diminished.

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17
Q

Concave mirror
When an object is kept at C

A

The image formed is real and inverted at C and is of the same size.

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18
Q

Concave mirror
When an object is placed between C and F

A

The image formed is beyond C larger and real and inverted.

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19
Q

Concave mirror
When an object is kept at F

A

The image formed would be at infinity and real and inverted larger.

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20
Q

Concave mirror
When the object is between F and P

A

The image formed is behind the mirror virtual and erect and enlarged

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21
Q

What are the uses of concave mirrors?

A

Used in shaving mirror headlight solar furnace and also by dentists.
Dentists need an enlarged, virtual image as the object is kept near the mirror the image formed is enlarged and erect.
In the solar furnace and headlight a strong parallel beam of light is required.

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22
Q

Convex mirror
When an object is at infinity

A

Image is formed at focus virtual and erect and highly diminished

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23
Q

Convex mirror
When the object is between infinity and Pole.

A

The image is formed between P and F virtual and erect smaller or diminished.

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24
Q

What are the uses of a convex mirror?

A

Used where a wide field of view is required like parking mirrors and rear view mirrors.

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25
Sign convention of spherical mirrors
Left of the mirror -ve Right of the mirror+ve Above principal axis+ve Below principal axis -ve
26
What is the mirror formula?
1/v + 1/u = 1/f u- obj distance v - image distance f - focal length
27
What is magnification?
It is the extent to which the image size has increased or decreased.
28
What is the formula of magnification?
m = hi/ho = -v/u
29
If magnification is positive then the image is .............
Virtual
30
If magnification is -ve image is ...................
Real
31
If m is 1 then the image is ................
Same size as the object
32
If m > 1 then the image is ...................
Enlarged
33
If m < 1 then image is
Diminished
34
The object distance is always ...............
-ve
35
The focal length of the concave mirror is
-ve
36
The focal length of the convex mirror is
+ve
37
What is a refraction?
When light travels from one medium to another it changes its direction and bends and this bending of light is called refraction
38
What is optical rearer or denser medium ?
Optical rearer medium has high speed of light and is less dense Optical denser medium has less speed of light as it is more denser
39
What are the reasons for refraction?
-Speed changes due to optical density. - Change in direction and medium
40
If light travels from rearer to denser it .........
Bends towards normal
41
If light travels from denser to rarer ...........
Bends away from normal
42
What are the laws of refraction?
I) The incident ray normal the refracted ray all lie on the same plane (plane not medium) II) Snell law - if the medium is same the sine of angle of incidence upon sine of angle of refraction is constant.
43
What is refractive index?
It is inversely proportioned to speed of light. Denoted by n or u
44
What is the refracted index of medium a with respect to medium b
Speed of light in medium b / speed of light in medium a OR Refractive index of medium a / refraction index of medium b
45
Speed of light in vacuum
3×10 with the power of 8 m/s
46
What is concave and convex lens ?
Concave lens diverges the light rays Convex lens converages the light rays
47
What are the parts of the lens ?
2 focus 2 centre of curvature and one optical centre - O
48
Parallel rays in a lens pass through
Focus
49
Focal length of concave lens
-ve
50
Focal length of covex mirror
+ve
51
Light ray passing through focus refracts
Parallel to principal axis
52
Light rays passing through optical centre
Stays the same
53
**CONVEX LENS** Object is at infinity then image at
Focus
54
**CONVEX LENS** Object is beyond C image at
BETWEEN C AND F
55
**CONVEX LENS** When objects at C images at
C
56
**CONVEX LENS** When obj is between C and F image is
Beyond C
57
**CONVEX LENS** When objects at F image at
Infinity
58
**CONVEX LENS** Object between F and P image
Virtual and erect
59
**CONCAVE LENS** When object at infinity
Image at focus
60
**CONCAVE LENS** Object at finite distance
Image between focus And O
61
What is lens formulae ?
1/v-1/u=1/f
62
What is the magnification of the lens?
m=hi/ho =-v/u
63
What is power ?
It is the reciprocal of focal length denoted by D Dipotre formula - 1/f when f in m and 100/f when f in cm
64
What is the total power upon combining two lens
P1+P2
65
What is the power of plane mirror
0
66
What is the focal length of plane mirror
♾️
67
What is absolute refractive index?
Refractive index with the respect to air