## Tuesday, 9 December 2014

### PHYSICS QUESTIONS ENERGY AND LIGHT

1. A swimmer climbs out of a swimming pool on a warm, dry day. Almost immediately he begins
to feel cold.
Why is this?
A The water allows a convection current to remove heat from his skin.
B The water takes latent heat from his body in order to evaporate.
C The water on his skin is a good conductor of heat.
D The water prevents infra-red radiation from reaching his body.
2. A substance consists of particles that are close together and moving past each other at
random. The average speed of the particles is gradually increasing.
What best describes the substance?
A a liquid being boiled to form a gas
B a liquid being heated
C a solid being heated

D a solid being melted to form a liquid
3. In a hydroelectric power station, water from a reservoir falls down a long pipe before entering
The turbines. The turbines then turn the generator.
What is the overall energy conversion?
A electrical energy into kinetic energy
B electrical energy into potential energy
C kinetic energy into chemical energy
D potential energy into electrical energy
4. Some of the more energetic molecules in a liquid leave the surface, leaving the rest of the
Liquid slightly cooler.
What is the name given to this process?
A boiling
B condensation
C evaporation
D freezing
5. When we talk about angles of incidence and reflection, we often talk about the normal. The normal to a surface is an imaginary line that is perpendicular to the surface. The normal line starts where the incident ray strikes the mirror. A normal line is drawn for you in the sample problem above.
a. Draw a diagram that shows a mirror with a normal line and a ray of light hitting the mirror at an angle of incidence of 60 degrees.
b. In the diagram above, label the angle of reflection. How many degrees is this angle of reflection?
6. Light strikes a mirror’s surface at 20 degrees to the normal. What will the angle of reflection be?
23.1
7. A ray of light strikes a mirror. The angle formed by the incident ray and the reflected ray measures 90 degrees. What are the measurements of the angle of incidence and the angle of reflection?

8. In a game of basketball, the ball is bounced (with no spin) toward a player at an angle of 40 degrees to the normal. What will the angle of reflection be? Draw a diagram that shows this play. Label the angles of incidence and reflection and the normal.
Use a protractor to figure out the angles of incidence and reflection for the following problems.