Electrical Principles and Technologies Part Three Flashcards

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1
Q

What is energy?

A

The ability to do work.

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2
Q

What is work?

A

The transfer of energy.

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3
Q

What is the Joule?

A

The unit of measure for energy.

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4
Q

What are the four common forms of energy?

A

1) chemical energy
2) electrical energy
3) mechanical energy
4) thermal energy

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5
Q

What is chemical energy?

A

Stored in chemicals and released when chemicals react. Potential/stored energy in foods, fuels, batteries, explosives.

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6
Q

What is electrical energy?

A

Energy of charged particles, transferred when electrons travel from place to place.

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7
Q

What is mechanical energy?

A

Energy of motion, energy possessed by an object because of its motion or its potential to move.

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8
Q

What is thermal energy?

A

Total kinetic energy of all particles in a substance. The faster a particle moves, the more kinetic energy.

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9
Q

What is the 2 cup analogy?

A

Compare two cups holding equal amounts of water, the one containing more thermal energy will feel warmer.

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10
Q

What is energy conversions?

A

All forms of energy can be converted to other forms.

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11
Q

What is the law of conservation of energy?

A

Energy cannot be created nor destroyed.

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12
Q

What is a thermocouple?

A

A device that converts thermal energy to electricity.

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13
Q

What is the Hans Oersted Demonstration?

A

1820: Compass needle deflected by magnetic field of a current carrying wire. Proved a current flowing through wire creates magnetic field around wire.

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14
Q

What did Michael Faraday do in 1831?

A

Made the first electric motor, proving electromagnetic force can produce continuous motion.

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15
Q

What is a permanent magnet?

A

Hard steel alloy which stays magnetic for a long time.

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16
Q

What is an electromagnet?

A

Coil of wire (usually with iron core) which has magnetic effects when attached to a current; can be turned off and on.

17
Q

How does a simple electro-motor work?

A
  • wrap piece of metal in wire
  • hook wires to a battery
  • reversing wire reverses the current which reverses the polarity of magnets
  • continuous motion
18
Q

What is an armature?

A

Rotating shaft with a coil wrapped around it.

19
Q

What is a commutator?

A

A split ring that breaks flow of electricity for a bit then reverses the flow in the coil. If contact if broken, so is the magnetic field.

20
Q

What are the brushes?

A

They reverse the flow of electricity through electromagnetic coil, make contact with commutator by “brushing” against it.

21
Q

How do the poles work in an electromotor?

A

Poles of the armature are attracted to opposite poles of a permanent magnet and spin towards it. At 180 degrees contact is broken and the poles reverse. The split-ring commutator break the flow, then reverses the current. Armature keeps spinning due to momentum, brushes break contact again poles keep reversing= continuous motion.

22
Q

What is DC?

A

Direct current- electrons flow one way (most battery operated things use DC)

23
Q

What is AC?

A

Alternating Current- electrons move back and forth 60 times/sec (ex.wall outlets)

24
Q

What are transformers?

A

A current carrying wire is wrapped around one side of an iron ring (core). This is the primary coil. A secondary coil of wire is wrapped around the other side of the core. Current flowing through the primary coil generates an electromagnetic field which induces a current in the secondary coil.

25
Q

What is a step-down transformer?

A

They reduce voltage. There are more windings on the primary coil than the secondary.

26
Q

What is a step-up transformer?

A

They increase voltage. There are fewer windings on the primary coil than the secondary.

27
Q

What is a DC generator?

A

Structurally same as a DC motor. If electricity is passed through a DC generator, it will spin like a motor.

28
Q

What is an AC generator?

A

As the motor turns, one side of the coil moves up between the magnets, the other side moves down. Current is induced in the coil. As the generator continues to rotate current is induced in the coil in the opposite direction due to slip rings. This reversal of current every 1/2 rotation generates alternating current.

29
Q

What are the types of generators?

A
  • wind
  • hydro electric
  • steam driven (nuclear, coal, geothermal, biomass)
30
Q

What is power?

A

The rate at which we use energy. It is measured in watts, also known as 1J/sec.

31
Q

How to calculate power?

A

P=IV
Power= Current(A)*voltage(V)

32
Q

What is energy?

A

The ability to do work. Measured in Joules (J).

33
Q

How to calculate energy?

A

E=Pt
Energy= Power(W)*time (sec)

34
Q

How do you calculate efficiency?

A

output energy(J)/Input energy(J) *100

Output divided by Input multiplied by a hundred

35
Q

What are kilowatt hours?

A

Also known as Kilojoules, they are a bigger unit of measure than Joules.

36
Q

What is energy dissipation (why is the outcome energy always smaller)

A

Lost due to useless energy such as sound or friction (thermal).

37
Q

Why is it important to buy products with energy efficient designs?

A

They use less electricity.

38
Q

Ways to increase efficiency?

A
  • reduce friction as much as possible
  • insulate from heat loss (heat energy)
  • use capacitors (formerly condensers)