Pre-laboratory Assignment: Experiment 20 Reflection and Refraction of Light 1. When light is incident on a reflective surface, what can be said about the angle and speed at which the light is reflected? (Information is in your ‘General Physics Laboratory Manual’ Chapt. 20) 2. At what angle is the normal drawn to the reflective surface or air-medium interface? 3. How are angles of incidence, angles of reflection and of refraction measured? 4. Describe what happens to a light ray as it enters from a medium of greater refractive index to a medium of lesser refractive index

1) ngle of incidence and reflection are equal,  light carries does not change

2) the angle of this line with respect to the surface is 90º

3) protractor

4)    n₂  sin θ₂ = n_1 sin θ₁,  light ray must have a greater angle than the incident ray ,

Explanation:

1) When light falls on a reflective surface, the angle of incidence and reflection are equal and as it travels in the same medium, the speed that the light carries does not change

2) The normal is a line perpendicular to the point of incidence of light, so the angle of this line with respect to the surface is 90º

3) Angles are measured with a protractor

4) When light passes from one medium to another, the speed of the ray changes due to the difference in the refractive index in each medium, due to this change in speed the transmitted light ray must have a greater angle than the incident ray , since the speed increases as the density of the medium decreases

          n₂  sin θ₂ = n_1 sin θ₁

answer: 802.3 kilo joules of energy represents 191.75 kilo calorie of energy.

explanation:

energy released during combustion of one mole methane = 802.3 kilo joules

if 1 kilo joule = 0.239006   kilo calorie

then ,802.3 kilo joule will be = 802.30.239006 kilo calorie

802.3 kilo joule = 191.75 kilo calorie

hence, the energy in kilo calorie is 191.75 kilo calorie.

fgravity=10x10=100n case 1

fgravity=30x20=600n case 2

6 times more