# 1.E: Self-Test 1

- Page ID
- 3265

- What are the tiny particles that matter is made of called?
- Compounds
- Atoms
- Ions
- Protons and neutrons

- What are elements called that have atoms with electrons that are easily freed?
- Ions
- Conductors
- Insulators
- Elements

- Which of the following best describes copper?
- Conductor
- Insulator
- Semiconductor
- Valence electron

- Why are insulators useful?
- They transport an electrical charge.
- They do not transport an electrical charge.
- They readily release valence electrons.
- They will ionize easily when subjected to voltage.

- In what units is current measured?
- Volts
- Amperes
- Ohms
- EMF

- A source of electromotive force can be from a chemical reaction.
- True
- False

- In a DC circuit the poles alternate from positive to negative.
- True
- False

- What is the device called that is used to turn a circuit on and off?
- A control
- A conductor
- A load
- A protector

- Which of the following best describes an electric motor?
- A control
- A load
- A fuse
- A conductor

Use Ohm’s law for the following questions.

E = I × R, where:

- Volts (V) is represented by “E” for electromotive force.
- Amperes (A) is represented by “I” for intensity of current.
- Ohms (Ω) is represented by “R” for resistance.

- If resistance in a circuit is 6 Ω and the pressure is 24 V, what is the current flow?
- 2 A
- 4 A
- 6 A
- 8 A

- If a circuit had a current flow of 8 A and the resistance is 20 Ω, what is the pressure in volts?
- 120 V
- 160 V
- 2.5 V
- 25 V

- If a circuit has a current flow of 5 A and a pressure of 120 V, what is the resistance?
- 24 Ω
- 12 Ω
- 6 Ω
- 3 Ω

Use the power formula for the following questions.

watts = volts × amps or P = E × I

- How much power will a heater produce if it uses 15 A in a 120 V electrical system?
- 1800 W
- 1500 W
- 900 W
- 1200 W

- How many amps will flow through a 60 W headlight bulb in a 24 V system?
- 6 A
- 2.5 A
- 25 A
- 8 A

- Use Ohm’s law to complete the following chart.
voltage

current

resistance

500 mA

240

12

1000

12

8 A

5

20 000

120

10

0.15 A

80

3

0.0002 A

- Use the power formula to complete the following chart.
power

voltage

current

1500 W

12.5 A

40 W

12 V

12 V

300 mA

200 W

10 A

96 W

12 V

12 V

40 A