Unit C | Topic 3.1-3.3 | Motors and energy

Question 1

Definition of:
Energy

Answer 1

The ability to do work

Question 2

Definition of:
Chemical energy

Answer 2

The energy found in chemical bonds (considered potential energy)

Question 3

Definition of:
Thermal energy

Answer 3

Is the total kinetic energy of all moving particles in a substance (basically the heat electrons produce because of friction)

Question 4

Definition of:
Electrical energy

Answer 4

The energy of charged particles

Question 5

Definition of:
Mechanical energy

Answer 5

The energy of an object because of its motion (or potential to move)

Question 6

What is the first law of thermodynamics?

Answer 6

Energy can’t be created or destroyed, only transferred

Question 7

Definition of:
Thermocouple

Answer 7

A device that converts thermal energy into electrical energy

Question 8

How does a thermocouple work?

Answer 8

When the metals are heated, the difference in conduction results in electricity flowing from one metal to the other

Question 9

Who invented the first electric motor?

Answer 9

Faraday

Question 10

How does an electromagnet work?

Answer 10

When electricity flows through a circuit, it aligns the elections in one direction like a magnet, creating a magnetic field.

Question 11

What are the tree components of an electromagnet?

Answer 11

1. Power source
2. Coil of wire
3. Metal core

Question 12

What are three ways to increase the strength of an electromagnet?

Answer 12

1. Increase the size of the core
2. Increase the strength of the current (+V)
3. Increase the # of coils around the the core

Question 13

What happens if the current is reversed in an electromagnet?

Answer 13

Magnetic field inverts
(North and South switch)

Question 14

Definition of:
Electric motor

Answer 14

A device that converts electrical energy into mechanical energy

Question 15

What components does an electric motor require?

Answer 15

1. An armature
2. A permanent magnet
3. Brushes
4. A commutator

Question 16

Definition of:
Commutator

Answer 16

A split ring that breaks the current for a moment then reverses the current to maintain rotation

Question 17

Definition of:
Brushes

Answer 17

Electrical contacts with the commutator that permit electrons to flow through the armature

Question 18

Definition of:
Permanent magnet

Answer 18

Creates a magnetic field with north and south poles, which interacts the the armature and causes it to spin

Question 19

Definition of:
Armature

Answer 19

A rotating shaft with a coil wrapped around it

Question 20

Definition of:
Alternating current

Answer 20

Current that flows back and forth 60 times a second

Question 21

Definition of:
Direct current

Answer 21

Current that only travels in one direction

Question 22

Who invented alternating current?

Answer 22

Nicola Tesla

Question 23

Who invented direct current?

Answer 23

Thomas Edison

Question 24

Definition of:
Transformer

Answer 24

A device that changes electricity from one voltage to another one

Question 25

Definition of:
Electromagnetic induction

Answer 25

Electrical current generated by moving a conductor through a magnetic field

Question 26

Definition of:
Generator

Answer 26

A device that converts mechanical energy into electrical energy

Question 27

What is the formula for Power?

Answer 27

P = I x V
Power = Current x Voltage

or

P = E / T
Power = Energy (joules) / Time (seconds)

Question 28

What is the formula for Cost of electricity?

Answer 28

Cost = Energy consumed (kW/hr) x $ charged per kW/hr

Question 29

What is the formula for effeciency?

Answer 29

Efficiency (%) = [Useful energy output / Total energy input] x 100

Question 30

What components are on an energuide manual?

Answer 30

1. Annual energy consumption of the appliance in kW/hr
2. The energy consumption indicator - compares the model to others in it’s class
3. Energy consumption of the most and least efficient appliances in its class
4. The type and capacity range of similar models compared

Question 31

What are two major ways to increase the energy efficiency of a device?

Answer 31

1. Decrease friction (using bearings and lubricants)
2. Adding more insulation to reduce heat loss