RAD Physics - Chapter 9: Electric Generations and Motors

electric generator

Device that converts mechanical energy to electrical energy, functioning on the principle of electromagnetic induction

1. Armature

2. Powerful electromagnet

3. Form of mechanical energy

3 components for electric generator to function?

Armature

Loop of wire?

alternating current generator

What does AC generator stand for?

steam turbine

What is a common form of mechanical energy?

1. single wire loop

2. slip ring

3. alternating current

3 components of a simple electric generator?

single wire loop

spins between magnets; each end connects to a slip ring

slip rings

connects wire to external circuit, produces alternating current (AC)

alternating current

current changes/reverses direction

withdraw alternating current

Purpose of the external current in AC generator?

maximum

When the wire (armature) moves perpendicular to the magnetic field (cuts across at 90°), the induced voltage (EMF) is ___

zero

When the wire moves parallel to the magnetic field, the induced voltage (EMF) is  ___

sine curve

the graph of the output of an AC generator is the ___

60 Hz (60 times per second) 

Frequency of our US alternating current (AC) generators?

Hertz

cycles per second?

two

For each rotation there are __ alternations of current 

120

1 Second = ___ alternations of current per second

Root Mean Square

What does RMS stand for?

effective

Rms means the same as ___

maximum

Peak means the same as ___

Impedance (ohms)

Total Resistance of AC Circuit is called?

V = IZ

Impedance formula?

1. True electrical resistance

2. Inductive reactance

3. Capacitive reactance

3 components of Impedance?

Direct Current generator

DC generator stands for?

1. A powerful magnet

2. Armature

3. Commutator

4. Form of mechanical energy (steam turbine)

What is needed for a DC generator? (4)

withdraw

External current is used to ___ current in a DC generator

AC: slip rings

DC: commutator

What different thing do you need in a DC generator vs AC generator?

above x-axis

Where is the line on the graph on a DC graph?

commutator

split metal ring with an insulator in between which forces current to go around external circuit in one direction only

AC current

Which is more common, AC or DC current?

1. AC can be easily transformed using transformers

2. AC can be sent long distances

2 advantages of alternating current?

high, low

AC can be sent at ___ voltage and ___ current, which means less energy lost as heat

P = I^2 x R

Power loss in the form of heat formula?

Electric motor

changes electrical energy into mechanical energy?

supply

External current is used to ___ current in an electric motor

1. powerful magnet

2. armature

3. commutator

4. a battery

What does an electric motor need?

motor

Motor operates on a ___ principle

Motor Principle

whenever a conductor carrying a current is placed in a magnetic field, there is a force or side thrust on the conductor

magnetic field of the current (a temporary magnet) interacts with the magnetic field of the permanent magnet

What causes the force on a conductor carrying a current in a magnetic field?

attract

If the magnetic fields are in opposite directions, they ___

repel

If they are in the same direction, they ___

The commutator reverses current, switching between attraction and repulsion

What makes the armature keep spinning?

motor principle

Motor effect means the same as ___

increase

Increase strength, ___ motor effect

increase

Increase length of conductor, ___ motor effect

increase

Increase the size of current, ___ motor effect

Right hand rule

___ answers the question which way will armature turn

supplied

In a simple electric motor, current is ___ by external circuit

heating device

In a back emf, the motor uses less current than a ___

2 types, Synchronous Motor & Induction Motor

How many types of alternating current motors are there? What are they?

supplying

In a synchronous motor, in the external circuit, we have an AC generator ___ the current

Synchronous Motor

In a ___ motor both armatures spin at the same time

x-ray timers

What are synchronous motors found in?

Stator & Rotor

What are the 2 parts of an induction motor?

Stator

made of pairs of electromagnets

Rotor

made of an iron core surrounded by copper bars

eddy currents

Flux linkage with copper bars creates ___

rotor

Eddy currents makes ___ spin

Eddy Current

swirling current

An induction motor

___  is used to rotate the anode in the x-ray tube

motor principle

Galvanometer operates on ___

DC, DC

Galvanometer is modified to measure ___ current (ammeter) & ___ voltage (voltmeter)

motor principle

Electrodynamometer operates on ___

AC, AC

Electrodynamometer is modified to measure ___ current (ammeter) & ___ voltage (voltmeter)

Dynamo

Another name for an electric generator is a __________.

mechanical, electrical

An electric generator converts __________ energy into __________ energy

electromagnetic induction

An electric generator operates through __________, or the setting up of an emf in a conductor as it cuts or is cut by magnetic flux.

armature

A coil of wire that is mechanically rotated in a magnetic field is called an __________.

slip ring

In a simple electric generator, each end of a single loop of wire is connected by a __________to an external circuit.

alternating current

A current that periodically reverses direction is called an __________.

rms (root mean square)

The __________ value of an alternating current is defined as that direct current which has the same heating effect in a resistor as the alternating current in question.

inductive reactance

The bucking tendency of inductance in an AC circuit is called __________.

capacitive reactance

The periodic reversal of polarity of a capacitor in an AC circuit offers resistance to the flow of current and is known as __________.

impedance

The total resistance of an AC circuit is called __________.

commutator

In a DC generator, a __________ is used to feed the current to the external circuit instead of slip rings.

above the x-axis

The wave form of generated DC current differs from that of AC current in that the part of the sine wave that is below the x axis in AC is now __________.

electrical, mechanical

An electric motor converts __________ energy into __________ energy.

force/side thrust

Whenever a conductor carrying an electric current is placed in a magnetic field, there is a __________ on the conductor.

increases

As the number of turns in the conductor increases, the motor effect __________.

increases

As the strength of the magnetic field increases, the motor effect __________

increases

As the size of the current increases, the motor effect __________

magnetic field, electric current, conductor movement

According to the right hand rule, when the thumb and first two fingers of the right hand are held so that each is at a right angle to the others, and the index finger points in the direction of the __________ while the middle finger points in the direction of the __________, the thumb will then point in the direction of __________.

generator

The back emf produced through electromagnetic induction when the coil of a motor rotates causes an electric motor to also act as a __________,

electromagnets

A stator is made up of __________.

rotor

A __________ is made up of a cylindrical iron core surrounded by copper bars.

galvanometer

The motor principle is used in the construction of the __________ which is used to measure DC current and DC voltage

electrodynamometer

The motor principle is used in the construction of the __________ which is used to measure AC current and AC voltage.