Exam IV Diagrams + Essay QA

Question 1

illustrate

the law of reflection

Answer 1

Question 2

illustrate

refraction

Answer 2

Question 3

illustrate

dispersion of white light through prism

Answer 3

Question 4

write 5-7 sentences describing:

formation of rainbows

Answer 4

rainbows are a result of light dispersion by many droplets.
1. sunlight incident on two sample raindrops emerges from them as dispersed light
2. the obsever sees the red light from the upper drop anf the violet light from the lower drop
3. millions of drops produce the whole spectrum of visible light
4. when your eye is located between the sun and a water drop region, the rainbow you see is the edge of a 3D cone that extends htrough the water drop region.

Question 5

write 5-7 sentences describing:

huygen’s principle

Answer 5

wavefronts are made up of tinier wavefronts—this idea is called Huygens’ principle
1. every point of a wavefront may be considered the source of secondary wavelets that spread out in all directions with a speed equal to the speed of
propagation of the waves
2. plane waves can be generated in water by successively dipping a horizontally held straightedge into the surface
3. as the width of the opening is narrowed, less of the incident wave is transmitted
4. the spreading of waves into the shadow region becomes more pronounced.

Question 6

write 5-7 sentences describing:

nuclear reactors

Answer 6

a nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions, used at power plants
1. reactors are simply nuclear furnaces that boil water to operate steam-driven generators
2. today’s fission reactors contain three components:
* the nuclear fuel is primarily U-238 plus about 3% U-235
* the control rods are made of a neutron-absorbing material, usually cadmium or boron
* water surrounding the nuclear fuel is kept under high pressure to keep it at a high temperature without boiling

Question 7

write 5-7 sentences describing:

rutherford’s gold foil experiment

Answer 7

in rutherford’s experiment, a beam of positively charged alpha particles was directed through a thin gold foil which led to the atomic nucleus discovery.
* when the piece of gold foil was hit with the alpha particles (positive charge), most of the particles went right through the gold foil. this indicates that the mass of the atom is concentrated in a small region within itself. thus, showing that the atoms were mostly empty space.

Question 8

essay question:

radioactivity

Answer 8

radioactivity is the process of nuclear decay (radioactive decay). It is nothing new in the environment and has been going on since
time zero, before humans emerged on earth. thus, making radioactivity natural. it warms Earth’s interior, it is in the air we breathe, and it is present in all rocks (some in trace amounts). it is known that radioactive elements emit three types of radiation: (i) α - alpha, positively charged helium
nuclei (ii) β - beta, negatively charged electrons, (iii) γ - gamma electromagnetic radiation. gamma rays and xrays are typically the most harmful to humans as they are damaging to our cells.