G10 Electric Motors and Generators

Question 1

two ways on how electric current can be induced in a coil of wire

Answer 1

by moving a magnet into and out of a stationary coil of wire, or

by moving the coil of wire near a stationary magnet

Question 2

a device capable of converting mechanical energy into electrical
energy. Understanding how voltage is induced in a loop of wire is essential in the
analysis of how it works.

Answer 2

generator

Question 3

As the magnet is introduced, the magnetic field strength inside the coil increases
and the induced current in the coil moves in one direction.

Answer 3

Inducing Current by Moving a Magnet Through a Coil of Wire

Question 4

As the magnet is pulled
out, the magnetic field strength falls and current is induced in the opposite
direction.

Answer 4

Inducing Current by Moving a Magnet Through a Coil of Wire

Question 5

As the magnet is continuously pushed in and pulled out, the strength of the voltage
continues to change.

Answer 5

Inducing Current by Moving a Magnet Through a Coil of Wire

Question 6

During this process, voltage alternately drops and rises,

creating an alternating voltage.

Answer 6

Inducing Current by Moving a Magnet Through a Coil of Wire

Question 7

The more frequent the magnet is moved in and out

of the coil, the stronger the alternating voltage produced.

Answer 7

Inducing Current by Moving a Magnet Through a Coil of Wire

Question 8

placing a stationary magnet near a rotating loop. It is easier to move the coil instead of moving the magnet. This is done by rotating a coil in a stationary magnetic field. This basic concept is the working principle behind electric generators.

Question 9

As the loop rotates, it interacts with varying magnetic field lines, similar to what it would experience if a magnet is introduced and pulled out of it.

Question 10

Fleming’s _-Hand Rule for Generators

Answer 10

Right

Question 11

Thumb =

Fleming’s Right-Hand Rule for Generators

Answer 11

direction of force

Question 12

Index finger =

Fleming’s Right-Hand Rule for Generators

Answer 12

direction of magnetic field

Question 13

Middle finger =

Fleming’s Right-Hand Rule for Generators

Answer 13

direction of current

Question 14

Mechanical energy exerted to rotate the coil generates electrical energy that can power a load such as a light bulb

Answer 14

Generator

Question 15

current produced alternates back and forth

Answer 15

AC Generator

Question 16

current produced is only in one direction

Answer 16

DC Generator

Question 17

first person to create a generator in 1831 using electromagnetic induction

Answer 17

Michael Faraday

Question 18

the generator he built is called the

Michael Faraday

Answer 18

Faraday disk

Question 19

built one of the first dynamos - the first practical electric generators - in 1832

Answer 19

Hippolyte Pixii

Question 20

the first practical electric generators - in 1832

Answer 20

dynamos

Question 21

modern dynamos were independently developed by them

Answer 21

Sir Charles Wheatstone

Question 22

modern dynamos were independently developed by them

Answer 22

Werner Von Siemens

Question 23

modern dynamos were independently developed by them

Answer 23

Samuel Alfred Varley

Question 24

invented the Ferranti- Thompson Alternator with the help of Lord Kelvin in 1882

Answer 24

Sebastian Ziani de Ferrant

Question 25

alternating current generators

Answer 25

“Alternators

Question 26

The production of a magnetic field by a current-carrying wire was first noted by _ _ _ in 1820 during one of his lectures.

Answer 26

Hans Christian Oersted

Question 27

Oersted placed a compass near a wire connected to a battery. When the switch is turned on, the compass needle deflects as the current flows through the wire. This shows that electric current generates _ _.

Answer 27

magnetic field

Question 28

One convenient rule in remembering the direction of magnetic field in a current carrying wire is the

Answer 28

Maxwell’s Right-Hand Grip Rule

Question 29

right thumb= | Maxwell’s Right-Hand Grip Rule

Answer 29

direction of the current

Question 30

direction of the curl of the remaining four fingers= | Maxwell’s Right-Hand Grip Rule

Answer 30

direction of the magnetic field

Question 31

is a current-detecting device that uses a stationary magnet mounted with moving coil attached to a needle. The greater the current present in the wire, the larger the deflection of the needle.

Answer 31

galvanometer

Question 32

The coil of the galvanometer rotates as current passes through it. A pointer attached to it also moves whenever the coil rotates. If there is no current flow, the coil and pointer are kept at zero position by a tiny spring.

Question 33

converts electrical energy into mechanical energy

Answer 33

Electric Motor

Question 34

current in an electric motor reverses direction each time the coil turns half-way

Answer 34

major difference between a galvanometer and a moto

Question 35

used to identify the direction of movement of the current-carrying wire if placed in a magnetic field

Answer 35

Fleming’s Left-hand Rule for Motors

Question 36

Thumb = | Fleming’s Left-hand Rule for Motors

Answer 36

direction of force

Question 37

Index finger = | Fleming’s Left-hand Rule for Motors

Answer 37

direction of magnetic field

Question 38

Middle finger = | Fleming’s Left-hand Rule for Motors

Answer 38

direction of current

Question 39

The figure shows that the flow of the current is from the battery → conducting brush X → split ring P → arm AB → arm CD → conducting brush Y → split ring Q

Question 40

The next figure shows the location of the parts of the electric motor after half rotation of the coil.

Question 41

Notice that the location of arm AB and CD is reversed.

Question 42

Also, the split ring Q now touches the brush X and the split ring P now touches the brush Y. This means that the flow of the current will be reversed after the half rotation.

Question 43

The current flow will be from D → C → B → A. in effect, the reverse current flow will also reverse the force acting on the arms AB and CD

Question 44

Therefore, the reversing of the current occurs every half rotation which creates a continuous rotating motion of an electric motor.

Question 45

are powered by direct current sources like batteries. In this type of motor, the coil of wire rotates while the magnetic field (produced by magnets or electromagnets) stays in one direction. are commonly used in applications where motors need to be externally controlled

Answer 45

DC Motors

Question 46

do not use brushes and commutators Unlike a DC motor, an _ _ has a rotating magnetic field and a stationary armature also has a longer lifespan and is usually utilized when there is a need for power at an extended period of time

Answer 46

AC Motors

Question 47

invented the very first rotating device(motor) in 1822 known as Barlow’s Wheel

Answer 47

Peter Barlow

Question 48

a freely rotating spiked wheel connected to a power source surrounded by a magnetic field from a horseshoe magnet

Answer 48

Barlow’s Wheel

Question 49

some assume that he is the first one to invent a commutated rotary machine with magnets in 1828

Answer 49

Anyos Jedlik

Question 50

He was able to build an oscillating electromagnetic motor in 1831 that he regarded as a “philosophical toy” - the first demonstration of continuous motion produced by magnetic attraction and repulsion

Answer 50

Joseph Henry

Question 51

first demonstration of continuous motion produced by magnetic attraction and repulsion

Answer 51

philosophical toy

Question 52

built the first “real” motor in 1834

Answer 52

Moritz Hermann Jacobi

Question 53

the first motor to deliver a remarkable mechanical output power

Answer 53

Jacobi’s motor

Question 54

invented the first practical motor in 1886

Answer 54

Frank Julian Sprague

Question 55

a non-sparking motor that maintained relatively constant speed under variable loads

Answer 55

Frank Julian Sprague's motor

Question 56

developed a three-phase system in which instead of only a single magnetic field acting on a coil of wire is present, three rotating magnetic fields will act on coils of wire causing it to produce mechanical energy

Answer 56

Nikola Tesla