Light

Question 1

Why does refraction occur?

Answer 1

Due to change in speed of light as it enters frm 1 transparent media t another

Question 2

What is light

Answer 2

Sensation of vision
Travels in straight lines
Form of energy

Question 3

Explain reflection of light along w laws

Answer 3

Bouncing back of light after striking a smooth polished surface
Angle i = angle r
Ir rr the normal at point of incidence lie at same point

Question 4

Feautures of plane mirror

Answer 4

Virtual erect
Same size as obj
Laterally inv
Img as far behind as obj in front of it

Question 5

What are spherical mirrors what are types

Answer 5

Reflecting surfaces are curved
Concave
Convex

Question 6

Terms of mirrors

Answer 6

Principal axis
Centre of curvature
Pole
Aperture
Radius
Focal length - pole pa dist
Principal focus

R = 2f

Question 7

Rules for img formation of mirrors

Answer 7

Rays appear parallel to pa passes thru f
Vice versa
Ray incident obliquely to pa reflected obliquely angle i = angle r
Passing thru c is reflected backwards

Question 8

Uses of concave mirror

Answer 8

Shaving mirror - bw p and f
Opthalmoscope - light beam directed thru pupils eyes making retina visible
Astronimical telescope
Headlights - light places at f
Solar furnaces - produces heat

Question 9

Uses of convex mirror

Answer 9

Inside buildings
Rear view- wider field view
Security purposes

Question 10

Sign convention of mirrors

Answer 10

Obj placed left side of mirror
Dist parallel to pa is measured frm p
Dist upward +ve dist rht +ve

Question 11

Sign convention of concave and convex

Answer 11

Concave
F -ve real u -ve real v -ve real +ve virtual
+ve -ve +ve

Question 12

Mirror formula
Magnification

Answer 12

1/f = 1/v + 1/u
M = hdash/ h = -v/u

Ht = -ve real +ve virtual

Question 13

Explain refraction of light and laws

Answer 13

Light travles obliquely frm 1 medium to another dir of propogation of light in 2 medium changes
Does not travel in same dir or speed for all media

All lie on same plane

Question 14

What is LD what does it depend on

Answer 14

Ld is perpendicular dist bw ir and er Angle of incidence
Nature of material

Question 15

Why is there ld is glass but not prism

Answer 15

Extent of bending of ray of light at opp parallel face of rec glass slab is = and opp

Question 16

What is refractive index formula

Answer 16

n12 = v2/v1 vice versa
Velocity = speed of light
RI unitless
RI = Extent of change in dir in a pair of media

Question 17

Where does light travel fastest

Answer 17

In vacuum/air = 3*10^8

Question 18

What is absolute RI
Formula

Answer 18

medium 1 = vacuum then c /v2

Question 19

na
ng
nw
nd

Answer 19

1
1.5
1.33
2.4

Question 20

What does RI depend on

Answer 20

Density of medium - ray of light will bend towards normal based on density
Wave length of light

Question 21

When ri increases
Decreases

Answer 21

speed of light decreases
Increases - bending of normal

Question 22

What is a lens and what are diff types of lens

Answer 22

A material bounded by 2 surfaces of which 1 or both forms a lens
Concave - curved inward, diverges , thicker at edges
Convex - curved outward, converges , thicker in middle

Question 23

Terms of lens

Answer 23

Centre of curvature, optical centre, pf - ray of light converges at a point or diverges frm a point
fl - dist bw o and pf
aperture
pa

Question 24

Sign convention of lens

Answer 24

Convex - f +ve, u -ve, v +ve(real) -ve(virtual)
Concave - f -ve u -ve v -ve

Question 25

Lens formula and magnification
Power of lens combined

Answer 25

1/v - 1/u = 1/ f
Hdash/ h = v/u
P1+P2
Convex = f +ve p +ve
Concave = f = -ve p = -ve

Question 26

What is power of lens

Answer 26

degree of convergence or divergence of light rays achieved by a lens

Question 27

Img form rules for lens

Answer 27

ray parallel to pa passes thru pf
vice versa
passing thru 0 will pass w no deviation