Light that enters the new medium <em>perpendicular to the surface</em> keeps sailing straight through the new medium unrefracted (in the same direction).
Perpendicular to the surface is the "normal" to the surface. So the angle of incidence (angle between the laser and the normal) is zero, and the law of refraction (just like the law of reflection) predicts an angle of zero between the normal and the refracted (or the reflected) beam.
Moral of the story: If you want your laser to keep going in the same direction after it enters the water, or to bounce back in the same direction it came from when it hits the mirror, then shoot it <em>straight on</em> to the surface, perpendicular to it.
Answer:
Explanation:
There will not be any internal reflection . it will be only refraction
critical angle = θ
Sinθ = 1 / μg
μg = 1.43 / 1.33 =
Sinθ = 1.33 / 1.43
= .93
θ = 68.44
angle of incidence i = 68.44 / 2
= 34.22
Sin i / Sin r = μw = 1.33 / 1.43
= .93
sin 34.22 / sinθ₁ = .93 , θ₁ is angle of refraction.
sinθ₁ = sin 34.22 / .93
= .5623 / .93
= .6047
θ₁ = 37 degree Ans
Answer:
the volume of liquid decreased due to evaporation from the exposed free surface of water so molecules got evaporated .
evaporation occurs at room temperature.
Answer:
Explanation:
The rod will act as pendulum for small oscillation .
Time period of oscillation

angular frequency ω = 2π / T
= 
b )
ω = 20( given )
velocity = ω r = ω l
Let the maximum angular displacement in terms of degree be θ .
1/2 m v ² = mgl ( 1 - cosθ ) ,
[ l-lcosθ is loss of height . we have applied law of conservation of mechanical energy .]
.5 ( ω l )² = gl( 1 - cos θ )
.5 ω² l = g ( 1 - cosθ )
1 - cosθ = .5 ω² l /g
cosθ = 1 - .5 ω² l /g
θ can be calculated , if value of l is given .