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BASIC ELECTRICITY AND ELECTRONICS

CHAPTER 1

Basic Components & Circuits

6. Most electronic products have components mounted on circuit boards with the wires literally printed on the board surface.

7. A short circuit is a no-resistance path across a power source, and causes damage to components and batteries.

8. Solder is a special metal that is melted to make solid electrical connections.

9. Schematics are engineering drawings of circuits using symbols.

1. The electric current is a measure of how much electricity is flowing in a wire, and is expressed in Amperes.

2. The voltage is a measure of the electric pressure exerted into a wire or circuit by a battery or other power source, and is expressed in volts.

3. Switches are used to turn on or turn off the flow of electricity in a circuit.

4. A light bulb converts electricity into light.

5. Electrical circuits are all combinations of series and parallel configurations.

SUMMARY OF CHAPTER 1:

Multiple Choice

The flow of electricity is measured in ___________.

• gallons

• minutes

• amperes

• volts

Multiple Choice

To turn on a switch, you ___________ it.

• voltage

• open

• pressurize

• close

Multiple Choice

A short circuit is . . .

• a special condition that improves circuit performance in most cases.

• an accidental no-resistance path between different parts of a circuit.

• the shortest wiring path between two points in a circuit.

• All of them.

Multiple Choice

Solder is . . .

• glue that holds components in place, it resists the flow of electricity.

• always applied by hand.

• a metal that is melted to make solid electrical connections.

• a special metal made of copper and other alloys that melts at a low temperature.

CHAPTER 2

MOTORS & ELECTRICITY

5. An electrical current that is changing is called an alternating current (AC). An electrical signal that is constant and unchanging is called a direct current (DC). The electricity in homes is AC power.

6. Static electricity can cause clothes to stick together. Lightning occurs when static electricity in clouds discharges into the ground.

7. Only a small amount of the electricity used by light bulbs is converted into light, the rest becomes heat.

1. An electric current flowing in a wire has a magnetic field.

2. A generator uses mechanical motion to create electricity and a motor uses electricity to create mechanical motion.

3. A fuse is a special wire that breaks when an excessively high current flows through it, used for safety.

4. Electrical outlets are 120V, and can supply enough current to kill people.

SUMMARY OF CHAPTER 2:

Multiple Choice

Fuses are needed for all of the following reasons except:

• They improve circuit performance.

• To prevent an electrical problem from starting a fire.

• To limit the current in a circuit.

• People don’t always use products correctly.

Multiple Choice

All of the following are caused by static electricity except:

• Lightning

• Erratic noises interrupting music on your AM radio.

• Clothes sticking together in the dryer.

• Blackouts

Multiple Choice

What is the most important benefit of electricity?

• Energy can be easily transported.

• Radio communication.

• Television.

• The Internet

Multiple Choice

Why do local governments have building codes regulating the electrical wiring of buildings?

• To make money for the government through building permit fees.

• To ensure the building will be safe after many years and different owners.

• To ensure local electricians will always have jobs.

• To meet standards imposed by the local power companies supplying the electricity.

CHAPTER 3

RESISTANCE

7. Materials which have very low resistance are called conductors. Materials which have very high values of resistance and are called insulators.
8. Photoresistors change their resistance when light shines on them.
9. All currents flowing through resistors produce heat in them.
10. OR, AND, NOR, NAND and NOT circuits are basic building blocks of computers.
11. Digital electronics uses numbers to represent an electronic signal. The accuracy of the digital representation depends on how accurately and how often the original signal was measured.
12. Computers store numbers using arrays of transistors that are switched on or off.

1. Resistors are used to limit and control the current in a circuit.
2. Resistance is a measure of how much something opposes the flow of electricity in a circuit, and is expressed in ohms.
3. Light emitting diodes (LEDs) are one-way, low-current light bulbs.
4. Placing resistors in series increases the total resistance. Placing resistors in parallel decreases the total resistance.
5. In a circuit, the current equals the voltage divided by the resistance. This is known as Ohm’s Law.
6. Power measures how much energy is moving through a circuit, it equals the voltage multiplied by the current and is expressed in Watts.

SUMMARY OF CHAPTER 3:

Multiple Choice

The following are characteristics of an LED except:

• They block current flow in one direction.

• They get brighter as current increases.

• They can handle very high currents.

• They can emit different colors of light.

Multiple Choice

To increase the current through a circuit, you . . .

• Increase the resistance.

• Decrease the watts.

• Increase the ohms.

• Increase the voltage.

Multiple Choice

Which of these is Ohm’s Law?

• Current equals Power divided by Resistance.

• Current equals Voltage divided by Resistance.

• Voltage equals Current divided by Resistance.

• All current flowing into a point must flow out of it.

Multiple Choice

Digital electronics . . .

• uses computers to process electronic information.

• uses a series of numbers to represent an electronic signal.

• always gives better performance at lower cost.

• always has a display with at least one digit.

Multiple Choice

Nearly all electricity eventually becomes . . .

• heat.

• information.

• garbage.

• chemical energy.