1. Physical Science EOCT Review Domain IV Waves, Electricity and Magnetism

2. Parts of a Wave

3. Mechanical (Longitudinal) Waves
Examples are sound waves and slinkys

4. Electromagnetic Waves (Transverse)
Electromagnetic waves are transverse waves which have both an electric and and magnetic effect.
The energy of the photons is directly proportional to the frequency.

5. Light Light is a form of electromagnetic radiation (EM)
EM spectrum shows the forms of radiation in order of increasing frequency (and energy) and decreasing wavelength

6. Color of Light
We see different colors depending on the frequency of light emitted or reflected
This is the reason blue flames are hotter than yellow. Blue has a higher frequency so more energy.

7. Sample Question
How are the frequency and wavelength related to the energy carried by waves?
Answer: Higher frequency waves have more energy while longer wavelength waves have less energy. Frequency and energy are directly related while wavelength and energy are inversely related. Radio waves (long wavelength) have less energy than gamma waves (high frequency).

8. Sample Question How are frequency and wavelength related?
Answer: Frequency and wavelength are inversely related. High frequency waves have short wavelengths.

9. Electromagnetic Wave (EM) versus Mechanical Wave
EM WAVE
does not require matter to transfer energy
CAN travel through a vacuum
example: light
MECHANICAL WAVE
does require matter to transfer energy
CANNOT travel through a vacuum
example: sound

10. Sample Question
Make a Venn Diagram to Compare electromagnetic and mechanical waves.
Sample Answer: Electromagnetic waves (light) do not require matter to transfer energy while mechanical waves (sound) require matter to transfer energy. In other words, EM waves will travel in a vacuum while mechanical waves will not.

11. Reflection of Light When light strikes a boundary, it reflects.
The angle at which the wave approaches a flat reflecting surface is equal to the angle at which the wave leaves the surface (like a bounce pass of a basketball).
Reflection results in image formation.

12. Diffraction
We say that the wave bends around the barrier, or that it changes directions.  Where the wave was traveling in a straight line before passing the barrier, it is now 'bent' or it changed direction after passing the barrier.
DIFFRACTION of a wave is the bending or redirection of the travel of the wave when it passes a barrier without changing the medium in which the wave is traveling.

13. Refraction of Light
Light waves travel faster in air than in water and slower in glass than water.
More dense = slower light
When light enters a different medium, speed changes and it bends.
Bending of light due to change in speed = REFRACTION

14. Sample Question Reflection only Refraction only
Both Reflection and Refraction
Neither Reflection or Refraction
The correct answer is “C” because some
The light will be reflected some will be absorbed
And therefore refracted

15. Sound and mediums
Sound travels fastest through solids. This is because molecules in a solid medium are much closer together than those in a liquid or gas, allowing sound waves to travel more quickly through it. In fact, sound waves travel over 17 times faster through steel than through air. The exact speed of sound in steel is 5,960 meters per second (13,332 mph)! But, this is only for the majority of solids. The speed of sound in all solids are not faster than in all liquids.
Remember that Density is the key to how
Fast it travels!

16. Wave Interference
CONSTRUCTIVE
the phenomenon which occurs when two waves meet while traveling along the same medium
constructive = waves add to produce a larger wave
destructive = waves cancel to produce a smaller wave
DESTRUCTIVE

17. The Doppler Effect
observed whenever the source of waves is moving with respect to an observer
an apparent change in frequency occurs
toward = higher frequency
away = lower frequency

18. Electricity Electrons carry a negative charge.
Lost electrons = positive charge
Gained electrons = negative charge
REMEMBER:
Like charges repel
Opposites attract

19. Static Electricity 3 causes: Friction Conduction Induction
If you charge a balloon by rubbing it on your hair, it picks up extra electrons and has a negative charge. Holding it near a neutral object will make the charges in that object move. If it is a conductor, many electrons move easily to the other side, as far from the balloon as possible. If it is an insulator, the electrons in the atoms and molecules can only move very slightly to one side, away from the balloon. In either case, there are more positive charges closer to the negative balloon. Opposites attract. The balloon sticks.

20. Electrical Circuits Current flows in a closed circuit
SERIES
Current flows in a closed circuit
Two types of circuits:
Series (single path)
Parallel (many paths)
PARALLEL

21. 2 types of electrical currents
Alternating Current AC
have electrons that can change direction
a gasoline-driven generator is an example
Direct current DC
Means to move continuously in the same direction
Car Batteries is an example
Ohm’s Law
Relates current, voltage and resistance

22. Sample Question
The correct answer is “B”

23. Electromagnet
One can make an electromagnet with a nail, battery, and wire
When current flows through the coiled wire, the nail becomes magnetized. The more wraps-the greater the energy.

24. Electric Generators
Faraday discovered that if an electric conductor, like a copper wire, is moved through a magnetic field, electric current will flow (be induced) in the conductor. So the mechanical energy of the moving wire is converted into the electric energy of the current that flows in the wire.
This is called electromagnetic induction

25. Sample Question
The correct answer is “A”

26. Sample Question
When a loop of wire is turned in a magnetic field, electrical charges move through the
wire, creating an electrical current. This is the basis for an electric generator, so answer D
is correct.

27. Figure Reference Distance versus Time Graph figures: source unknown
Forces figure: retrieved from
Determining the Net Force figure: retrieved from
Newton’s Laws, Gravity, Work, Types of Mechanical Energy, Conservation of Energy, Light, Interference, and Doppler Effect figures: retrieved from
Electrical Circuits figures: retrieved from
Electromagnet figure: source unknown