Electrical theory

Question 1

What is the smallest part of any material made up of?

Answer 1

Molecules which are made up of one or more atoms

Question 2

How is an atom made up?

Answer 2

An atom is made up a central core containing protons surrounded by orbiting electrons

Question 3

How are protons and electrons charged?

Answer 3

Protons are positively charged and electrons are negatively charged

Question 4

An electrically neutral atom has how many electrons per protons?

Answer 4

An electrically neutral atom has as many positive (+) protons as there are negative (-) electrons

Question 5

If material is connected across a battery how will the positive and negative terminals react to electrons?

Answer 5

The positive plate attracts electrons whilst the negative plate repels them

Question 6

Describe electric current

Answer 6

The uniformed flow of electrons through a conductor is referred to as electric current

Question 7

What is Electromotive force?

Answer 7

Provides a difference in potential between two open terminals

Question 8

What is resistance?

Answer 8

Resistance is the opposition to the flow of current

Question 9

How is current flow proportional to the applied voltage?

Answer 9

Current flow in a circuit is directly proportional to applied voltage and inversely proportional to the resistance

Question 10

What is potential difference defined as?

Answer 10

potential difference is defined as difference across two terminals measured in volts

Question 11

What is Kirchoffs voltage law?

Answer 11

The algebraic sum of all voltages around a circuit is equal to zero (or supply voltage)

Question 12

What is Kirchoffs current law?

Answer 12

The sum of all currents arriving at a point must equal the sum of currents leaving that point

Question 13

What is common in a parallel circuit? What is common in a series circuit?

Answer 13

Current is common in a parallel circuit Voltage is common in a series circuit across the resistors

Question 14

What are the 3 voltage formulas?

Answer 14

V = (√P X R) V = (P / I) V = (I X R)

Question 15

What are the three current formulas?

Answer 15

I = (V / R) I = (P / V) I = (√ P / R)

Question 16

What are the three power formulas?

Answer 16

P = (V x I) P = (V² / R) P = (I² x R)

Question 17

What are the three resistance formulas?

Answer 17

R = (V / I) R = (V² / P) R = (P / I²)

Question 18

Draw a diagram as to how an ammeter would be connected to an electrical circuit

Answer 18

Question 19

Draw a diagram as to how a voltmeter should be connected in an electrical circuit

Answer 19

Question 20

Draw a diagram as to how a wattmeter should be connected in an electrical circuit

Answer 20

Question 21

Draw a diagram of how power factor is measured in a circuit

Answer 21

Question 22

Draw a diagram as to how an energy meter should be connected in an electrical circuit

Answer 22

Question 23

What is the unit of measurement and formula for magnetic flux density

Answer 23

Flux density, ß = flux (Weber, Φ)

Area (m2)

Teslas abbreviated to T

Question 24

Draw a picture of a current carrying conductor with flux line away from the user

Answer 24

Question 25

Draw a picture of a current carrying conductor with magnetic field current lines going towards the user

Answer 25

Question 26

Draw a picture of two current carrying conductors in a field coil attracting to one another

Answer 26

Question 27

Draw a picture of two current carrying conductors in a field coil opposing one another

Answer 27

Question 28

Draw a picture of maxwells screw rule

Answer 28

Question 29

Draw an example of a current carrying conductor using flemmings right hand generator rule

Answer 29

Question 30

Draw the force acting on a current carrying conductor with direct of rotation and current direction with flux lines going from north to south pole

Answer 30

Question 31

What is the formula for mechanical force exerted on the conductor measured in newtons

Answer 31

Question 32

What is the formula for EMF calculation?

Answer 32

E = B x L x V Measured in volts

Question 33

What is the formula for Frequency in a generator?

Answer 33

F = n X P F = Frequency in Hz N = Speed in revolutions per second P = Number of poles in pairs ( 1- & 1+ is a pair)

Question 34

Draw a picture of a sign wave including 1 cycle with peak voltages and peak to peak voltages

Answer 34

Question 35

What is the formula frequency and the formula for time period in reference to AC sine waves

Answer 35

Frequency = 1 / Time Period Time Period = 1 / Frequency

Question 36

What is the Formula to calculate the V avg and I avg in an AC sine wave?

Answer 36

V avg = 0.637 x V peak I avg = 0.637 x I peak

Question 37

What are the formulas for V Rms & I Rms when using an AC sine wave?

Answer 37

V Rms = 0.707 x V Peak I Rms = 0.707 x I Peak

Question 38

What is the formula for V Peak and I Peak when using an AC sine wave

Answer 38

V Peak = 1.414 x Vrms I Peak = 1.414 x Irms

Question 39

In electron current theory what way does electrons flow?

Answer 39

From the negative terminal to the positive terminal

Question 40

What are the 3 effects of electrical current?

Answer 40

Heating Magnetic Chemical

Question 41

What is conventional current flow?

Answer 41

When current flows from the positive terminal to the negative

Question 42

What is the formula for calculating V AVG with regards to a sine wave?

Answer 42

V Avg = V Peak x 0.636

Question 43

What is the definition of a coloumb? and give an example of a formula

Answer 43

the quantity of electrcity passing through and electrical circtuit. 1 Coloumb = 1 ampere per second Q = I x T

Question 44

Give a formula for frequency with regards to sine wave

Answer 44

Frequency = 1 / Time