Electrical Principles and Technologies Part Two

Question 1

What are Insulators?

Answer 1

Electrons are tightly bound to the nucleus, allowing little movement. (wood, rubber, air)

Question 2

What are conductors?

Answer 2

Electrons are free to move to the positive terminal when a voltage source is applied.

Question 3

How do neon signs work?

Answer 3

Usually gas would be an insulator but when current is applied, the electrons are excited and free themselves from the atoms. Creates a mixture of charged particles which conducts electricity.

Question 4

What are semi conductors?

Answer 4

At high temps they act like conductors, at low temps they act like insulators. (germanium, silicon, etc)

Question 5

What are superconductors?

Answer 5

Perfect conductors (no resistance). Some metals act as superconductors at extremely low temperatures.

Question 6

What is resistance?

Answer 6

Allow current to pass through but provides resistance, limiting the current.

Question 7

What is a switch?

Answer 7

A device that allows the flow of electrons or when the switch is open there is no flow, because there is a gap.

Question 8

What is a rheostat?

Answer 8

It is used to change the electron flow gradually. (ex. dimmer switch)

Question 9

What is the unit of resistance?

Answer 9

The Ohm

Question 10

What does Ohm’s law state as long as the temperature stays the same.

Answer 10

• the resistance of a conductor stays constant
• the current is directly proportional to the voltage applied

Question 11

How to calculate voltage, current, or resistance?

Answer 11

V= I*R v= voltage
I= V/R I= current (amp)
R= V/I R= Resistance

Question 12

Two most common types of resistors?

Answer 12

1) Wire wound: the larger and thinner the wire the higher the resistance
2) Carbon-composite: by varying composition and diameter, different resistances are available.

Question 13

What do voltmeters do?

Answer 13

They measure voltage differences (voltage drop) in volts.

Question 14

What do ammeters do?

Answer 14

Measure small currents.

Question 15

What do multimeters do?

Answer 15

can measure voltage, current, and resistance in a circuit.

Question 16

Parts of a circuit?

Answer 16

1. A source provides energy and supply of electrons for circuit.
2. a conductor provides a path for current.
3. a switching mechanism controls current flow, turning it on and off or directing it into different parts of the circuit.
4. a load converts electrical energy into another form of energy.

Question 17

What is an open circuit?

Answer 17

The switch is open, the circuit is off.

Question 18

What is a closed circuit?

Answer 18

The switch is closed, the circuit is on.

Question 19

What is a series circuit?

Answer 19

• one pathway for current
• entire circuit shuts down if there is a single break
• adding components increases resistance and decreases the current

Question 20

What is a parallel circuit?

Answer 20

• multiple pathways for current
• components in circuit can have own pathway
• adding resistors decreases total resistance of the circuit

Question 21

What are microcircuits?

Answer 21

Transistors are used with 3 layers of specially treated silicon with the middle layer receiving a small voltage, allowing it to control the voltage in the outer layers. This allows the transistors to act as switches.