UNIT V STUDY GUIDEElectricity & Magnetism

ANSWER KEY

1. Electricity is basically moving ____________.

• electrons

2. What is resistance?

• The opposition posed by a material to the flow of current.

3. What are the two factors of a wire that determine resistance?

• Length• Area (diameter)• Additional factors –

Temperature & Material Type.

4. Resistance is measure in what unit?

• Ohms (Ω)

5. A closed path that allows current to flow is called a __________.

• Circuit

6. Describe the difference between a parallel and series circuit?

• Circuit

7. What are examples of when you would use each type of circuit?

• Series – used for things with batteries.• Parallel – used around the

house; when things get their power from generators.

8. What is the name of a device used to prevent overheating of circuits?

• Resistor

9. What is AC?

• Alternating Current• Electron direction is constantly

flipping; electric field is changing directions.

10. What is DC?

• Direct Current• Electrons flow & electric field is

in one direction.

11. Which (AC or DC) is a battery?

• DC (Direct Current)

12. What “makes” AC?

• Generators

13. What does an electric motor do? (Hint: what form of energy does it start with and then convert to?)

• Converts mechanical energy into electrical energy.

14. What are the charges of electrons, protons, and neutrons? Why are electrons the easiest to “remove”?

• e- negative• p+ positive• n0 neutral• Electrons are easiest because

they are in the electron cloud.

15. What is the difference between conductors and insulators?

• Conductors allow the flow of electric current.• Insulators resist the flow of

electric current.

16. What is the definition of current?

• The rate at which charges move through a conductor.

17. What is the unit of current?

• Amperes / Amps (A)

18. What is the equation to calculate voltage?

•V = I·R

19. What is the voltage if the current is 10 amps and the resistance is 2 ohms?

• 20 volts

20. If 2 resistors are in series, what mathematical function must you use to determine the “equivalent resistance”?

• REQ = R1 + R2 + …

21. If one light goes and the others go out, what type of circuit do you have?

• Series

22. How can you induce current in a wire with a magnet?

• By moving the magnet back and forth (changing the electric field)

23. How would you make an electromagnet?

• By wrapping a wire supplied with current around an iron core.

24. Be able to draw series and parallel circuits.

SERIES EXAMPLE: PARALLEL EXAMPLE: