Light Flashcards
Why does refraction occur?
Due to change in speed of light as it enters frm 1 transparent media t another
What is light
Sensation of vision
Travels in straight lines
Form of energy
Explain reflection of light along w laws
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
Feautures of plane mirror
Virtual erect
Same size as obj
Laterally inv
Img as far behind as obj in front of it
What are spherical mirrors what are types
Reflecting surfaces are curved
Concave
Convex
Terms of mirrors
Principal axis
Centre of curvature
Pole
Aperture
Radius
Focal length - pole pa dist
Principal focus
R = 2f
Rules for img formation of mirrors
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
Uses of concave mirror
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
Uses of convex mirror
Inside buildings
Rear view- wider field view
Security purposes
Sign convention of mirrors
Obj placed left side of mirror
Dist parallel to pa is measured frm p
Dist upward +ve dist rht +ve
Sign convention of concave and convex
Concave
F -ve real u -ve real v -ve real +ve virtual
+ve -ve +ve
Mirror formula
Magnification
1/f = 1/v + 1/u
M = hdash/ h = -v/u
Ht = -ve real +ve virtual
Explain refraction of light and laws
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
What is LD what does it depend on
Ld is perpendicular dist bw ir and er Angle of incidence
Nature of material
Why is there ld is glass but not prism
Extent of bending of ray of light at opp parallel face of rec glass slab is = and opp
What is refractive index formula
n12 = v2/v1 vice versa
Velocity = speed of light
RI unitless
RI = Extent of change in dir in a pair of media
Where does light travel fastest
In vacuum/air = 3*10^8
What is absolute RI
Formula
medium 1 = vacuum then c /v2
na
ng
nw
nd
1
1.5
1.33
2.4
What does RI depend on
Density of medium - ray of light will bend towards normal based on density
Wave length of light
When ri increases
Decreases
speed of light decreases
Increases - bending of normal
What is a lens and what are diff types of lens
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
Terms of lens
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
Sign convention of lens
Convex - f +ve, u -ve, v +ve(real) -ve(virtual)
Concave - f -ve u -ve v -ve
Lens formula and magnification
Power of lens combined
1/v - 1/u = 1/ f
Hdash/ h = v/u
P1+P2
Convex = f +ve p +ve
Concave = f = -ve p = -ve
What is power of lens
degree of convergence or divergence of light rays achieved by a lens
Img form rules for lens
ray parallel to pa passes thru pf
vice versa
passing thru 0 will pass w no deviation
