Electricity - Section 3

Question 1

What is energy?

Answer 1

The ability to do work

Question 2

What are four common forms of energy?

Answer 2

Chemical Energy
Electrical Energy
Mechanical Energy
Thermal Energy

Question 3

What is the law of conservation of energy?

Answer 3

This law states that energy is neither created nor destroyed, but can be changed from one form to another

Question 4

What energy conversions happen naturally?

Answer 4

Our bodies run on chemical. The chemical energy can be converted into mechanical energy as we move and into thermal energy as our body temperatures rise

Question 5

How can chemical energy be transferred into electrical energy?

Answer 5

Through a battery

Question 6

What is a thermocouple?

Answer 6

Is a device that converts thermal energy into electrical energy

Is usually composed of two different, heat-conducting metals that are joined together. Heat is transferred from one metal to the other and electricity also flows from one metal to another

Question 7

What is a magnet?

Answer 7

A substance (usually iron) that has an attraction to other iron-containing objects

Question 8

What are permanent magnets?

Answer 8

Has a North and South Pole, and forms lines of force between the poles

Like poles repel, opposite poles attract

Permanent magnets are not usually very strong

Question 9

What are electromagnets?

Answer 9

These are formed when an electrical current is run through a coiled conducting wire, usually wrapped around a magnetic core

The direction of the current needs to switch in order to keep the electromagnet spinning in the magnetic field

Question 10

What are some factors that increase the strength of an electromagnet?

Answer 10

More coils of wire wrapped around the core
More current running through the wire
Permeable core (made of iron)

Question 11

What are some common uses for electromagnets?

Answer 11

Motors
Electric doorbells
I’m junkyards to pick up scrap metal

Question 12

What is an electric motor?

Answer 12

Device that converts electrical energy into mechanical energy

Question 13

What are the components of a basic electromagnetic motor?

Answer 13

Armature
Commutator
Brush

Question 14

What is an armature?

Answer 14

The electromagnet, composed of a rotating shaft and coil in a motor or generator

Question 15

What is a commutator?

Answer 15

A spilt ring in a motor that the flow of electricity for a moment, causing a reversal in the direction of the electrical current

Question 16

What is a brush?

Answer 16

Mechanism that makes electrical contact with the moving commutator in a motor

Question 17

What is a direct current (DC)?

Answer 17

Electricity that flows in only one direction

Question 18

What is an alternating current (AC)?

Answer 18

Electricity that flows back and forth (changes direction)

Question 19

What are transformers?

Answer 19

Transformers are used to change the amount of AC voltage with very little energy loss

Question 20

What are the two types of transformers?

Answer 20

Step-up transformers

Step-down transformers

Question 21

How does a step-up transformer work?

Answer 21

Has a primary coil of wire coming from the generator, wrapped around one side of an iron core ring, which produces an alternating magnetic field. The secondary coil is wrapped around the other side of the same iron ring

The magnetic field from the primary coil would induce an electrical current on the secondary coil, therefore the voltage will be increased

Question 22

How does a step-down transformer work?

Answer 22

The primary coil has a larger number of wraps than the secondary coil, which reduces the voltage prior to entering buildings and houses

Question 23

What is a generator?

Answer 23

Converts mechanical energy to electrical energy

Question 24

What is motor?

Answer 24

Converts electrical energy to mechanical energy

Question 25

What is power?

Answer 25

The rate at which a device converts energy from one form to another

The faster a device converts energy, the greater it’s power rating

Question 26

What are the formulas when calculating power, current, or voltage?

Answer 26

P = I x V
I = P/V
V = P/I

Question 27

What units of measurement are power, current, and voltage measured in?

Answer 27

Power: watts
Voltage: volts
Current: amps

Question 28

What is the formula to calculate energy?

Answer 28

E = P x t

Question 29

What is efficiency?

Answer 29

The ratio of the useful energy output from a device to the total energy input from the energy source providing the energy

Usually expressed as a percent

Question 30

What is the formula to calculate efficiency?

Answer 30

Efficiency = useful energy output/energy output x 100

Question 31

How do you convert Watts to Kilowatts?

Answer 31

divide by 1000