Electricity

Question 1

2 Semi Conductors

Answer 1

Silicon, Germanium

Question 2

Difference between EMF and Terminal Voltage

Answer 2

EMF: Force that converts energy into electricity.

PD: Amount of energy transferred between two points in a circuit

Question 3

What is capacitance measured in?

Answer 3

Farad

Question 4

What is the unit of Inductance?

Answer 4

Henry

Question 5

Low Pass RC Filter

Answer 5

Voltage divider that filters out higher frequency signals

Question 6

High Pass RC Filter

Answer 6

Voltage divider to remove lower frequencies

Question 7

Barrier potential of Silicon

Answer 7

0.6V

Question 8

Barrier potential of Germanium

Answer 8

0.2V

Question 9

EM Induction Principle

Answer 9

An EMF or PD is induced when a conductor moves through a magnetic field or a changing magnetic field cuts through a stationary conductor

Question 10

Faradays Law

Answer 10

the magnitude of the induced EMF is proportional to the rate of change of the magnetic field.

Question 11

Lenz Law

Answer 11

It states that the direction of the induced current in the coil will be always in such a way that it opposes the change which produces the current.

Question 12

Copper Loss

Answer 12

Loss of conductivity in transformer windings due to resistance of the copper.

Question 13

Eddy Currents

Answer 13

loops of electrical current that are created in a conductor when there is a change in the magnetic field, or when the conductor moves through a magnetic field.

Question 14

What does a laminated core do to the eddy current

Answer 14

Reduces the lass due to eddy currents dramatically.

Question 15

2 roles of a diode

Answer 15

Ensures current only flows in one direction.
Turns AC into DC (rectification)

Question 16

How do we reduce the output ripple in a diode bridge

Answer 16

Add capacitor in parallel with load

Question 17

4 conditions for a generator to be connected in parallel

Answer 17

Frequency of all generators is the same.
Voltages of the generator are equal.
Phase sequence must be the same.
They must be In-Phase.

Question 18

How is initial excitation achieved in brushless generators

Answer 18

A permanent magnet field excites the alternator as it rotates.

Question 19

How do we correct an imbalance in reactive power (kVAR)

Answer 19

Increase or decrease the torque

Question 20

How do we correct an imbalance of real power?

Answer 20

Increase or decrease the field current

Question 21

What are the conditions required for self excitation of a shunt connected to a DC generator?

Answer 21

There must be enough Residual Magnetism (flux) in the field poles.

Question 22

How do we rectify output?

Answer 22

Commutators and or diode bridge