Unit D Electrical Principles: 3.0

Question 1

What is the definition of energy?

Answer 1

The ability to do work

Question 2

What are the 4 common forms of energy?

Answer 2

Chemical Energy
Electrical Energy
Mechanical Energy
Thermal Energy

Question 3

Explain Chemical energy

Answer 3

• The energy stored in chemicals.
• This is a form of potential or stored energy.
• This energy is released when chemicals react.

Question 4

Explain electrical energy

Answer 4

• The energy of charged particles.
• Electrons are negatively charged.
• Electrical energy is transferred when electrons travel from place to place.

Question 5

Explain mechanical energy

Answer 5

• The energy possessed by an object because of its motion or its potential to move.
• A thrown baseball has mechanical energy because of its movement and its potential to fall.

Question 6

Explain thermal energy

Answer 6

• The total kinetic energy of all the particles in a substance.
• The faster a particle moves, the more kinetic energy it has.
• Compare two cups holding equal amounts of water: the one containing more thermal energy will feel warmer.

Question 7

What is the type of energy found in food?

Answer 7

Chemical energy

Question 8

What is a thermocouple?

Answer 8

A device that can convert thermal energy to electrical energy.

Question 9

How does a thermocouple work?

Answer 9

• 2 different metals that conduct heat at different rates are joined together
• When they are heated the difference in conduction results in electricity flowing from one metal to another

Question 10

Why are thermocouples useful?

Answer 10

Thermocouples are very useful for measuring temperatures in areas that are difficult to access or that are too hot for a liquid-filled glass thermometer.

Question 11

How did early scientists make electromagnets?

Answer 11

By winding a current carrying wire into a coil around an iron core and putting electricity through it.

Question 12

How do electromagnets keep spinning in an electric field?

Answer 12

By switching the direction that the current travels. That way it will align with the north and south fields so it will have to keep turning.

Question 13

How do electric motors reverse the flow of electricity?

Answer 13

They use commutators and brushes

Question 14

What is a commutator?

Answer 14

The commutator is a split ring that breaks the flow of electricity for a moment and then reverses the connection of the coil

Question 15

What is a brush?

Answer 15

The part of an electric motor connected to the split rings and the power source usually made of carbon

Question 16

What is the armature?

Answer 16

The rotating shaft with coils wrapped around it.

Question 17

Explain how an electric motor works

Answer 17

Electricity runs through a wire to brushes which are connected to a split ring commutator. The split ring is connected to a coil that is wrapped around an armature. The electricity running through the coil creates an electric field which attracts magnets which cause it to spin to align with the electric fields.

Question 18

What is direct current?

Answer 18

When electricity runs in only one direction

Question 19

What is alternating current?

Answer 19

Current that flow back and forth 60 times per a second

Question 20

What are transformers?

Answer 20

They change the amount of voltage with hardly any energy loss

Question 21

Why are transformers necessary?

Answer 21

Because power lines carry very high voltage nd it must be transformed down before it reaches houses.

Question 22

How does a transformer work?

Answer 22

A primary coil, with a lot of electricity flowing through it, is wrapped around an iron core with a secondary coil wrapped around the other side with fewer loops. If the loops are less than the voltage goes down.

Question 23

What is electromagnetic induction?

Answer 23

When electrical current could be generated by moving a conducting wire through a magnetic field.

Question 24

What does a generator use to function?

Answer 24

Electromagnetic induction

Question 25

Explain a how a generator work?

Answer 25

By moving a coil of wire past permanent magnets. As long as it keeps turning electricity will be produced. The faster you turn the more current that will be generated.

Question 26

What is the difference between a DC generator and an AC generator?

Answer 26

The central axle of an AC generator has a loop of wire that is attached to two slip rings. The slip rings create an alternating current.

Question 27

What is power?

Answer 27

The rate at which a device converts energy

Question 28

What is the unit of power?

Answer 28

Watt

Question 29

What is the formula to find power?

Answer 29

Volts x Current (amps)

Question 30

What is the unit for energy?

Answer 30

Joules

Question 31

What is the formula for energy?

Answer 31

Power x time (in seconds)

Question 32

What is the law of conservation of energy?

Answer 32

Energy cannot be created or destroyed. Energy does not just appear or disappear—it can only be transformed from one form to another.

Question 33

Why aren’t machines 100% efficient?

Answer 33

Because of friction

Question 34

What is efficiency?

Answer 34

The efficiency of a device is the ratio of the useful energy that comes out of a device to the total energy that went in

Question 35

What is the formula for efficiency?

Answer 35

Useful output energy (joules)/ input energy (joules)