Electrical theory Flashcards
What is the smallest part of any material made up of?
Molecules which are made up of one or more atoms
How is an atom made up?
An atom is made up a central core containing protons surrounded by orbiting electrons
How are protons and electrons charged?
Protons are positively charged and electrons are negatively charged
An electrically neutral atom has how many electrons per protons?
An electrically neutral atom has as many positive (+) protons as there are negative (-) electrons
If material is connected across a battery how will the positive and negative terminals react to electrons?
The positive plate attracts electrons whilst the negative plate repels them
Describe electric current
The uniformed flow of electrons through a conductor is referred to as electric current
What is Electromotive force?
Provides a difference in potential between two open terminals
What is resistance?
Resistance is the opposition to the flow of current
How is current flow proportional to the applied voltage?
Current flow in a circuit is directly proportional to applied voltage and inversely proportional to the resistance
What is potential difference defined as?
potential difference is defined as difference across two terminals measured in volts
What is Kirchoffs voltage law?
The algebraic sum of all voltages around a circuit is equal to zero (or supply voltage)
What is Kirchoffs current law?
The sum of all currents arriving at a point must equal the sum of currents leaving that point
What is common in a parallel circuit? What is common in a series circuit?
Current is common in a parallel circuit Voltage is common in a series circuit across the resistors
What are the 3 voltage formulas?
V = (√P X R) V = (P / I) V = (I X R)
What are the three current formulas?
I = (V / R) I = (P / V) I = (√ P / R)
What are the three power formulas?
P = (V x I) P = (V² / R) P = (I² x R)
What are the three resistance formulas?
R = (V / I) R = (V² / P) R = (P / I²)
Draw a diagram as to how an ammeter would be connected to an electrical circuit
Draw a diagram as to how a voltmeter should be connected in an electrical circuit
Draw a diagram as to how a wattmeter should be connected in an electrical circuit
Draw a diagram of how power factor is measured in a circuit
Draw a diagram as to how an energy meter should be connected in an electrical circuit
What is the unit of measurement and formula for magnetic flux density
Flux density, ß = flux (Weber, Φ)
Area (m2)
Teslas abbreviated to T
Draw a picture of a current carrying conductor with flux line away from the user
Draw a picture of a current carrying conductor with magnetic field current lines going towards the user
Draw a picture of two current carrying conductors in a field coil attracting to one another
Draw a picture of two current carrying conductors in a field coil opposing one another
Draw a picture of maxwells screw rule
Draw an example of a current carrying conductor using flemmings right hand generator rule
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
What is the formula for mechanical force exerted on the conductor measured in newtons
What is the formula for EMF calculation?
E = B x L x V
Measured in volts
What is the formula for Frequency in a generator?
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)
Draw a picture of a sign wave including 1 cycle with peak voltages and peak to peak voltages
What is the formula frequency and the formula for time period in reference to AC sine waves
Frequency = 1 / Time Period
Time Period = 1 / Frequency
What is the Formula to calculate the V avg and I avg in an AC sine wave?
V avg = 0.637 x V peak
I avg = 0.637 x I peak
What are the formulas for V Rms & I Rms when using an AC sine wave?
V Rms = 0.707 x V Peak
I Rms = 0.707 x I Peak
What is the formula for V Peak and I Peak when using an AC sine wave
V Peak = 1.414 x Vrms
I Peak = 1.414 x Irms
In electron current theory what way does electrons flow?
From the negative terminal to the positive terminal
What are the 3 effects of electrical current?
Heating
Magnetic
Chemical
What is conventional current flow?
When current flows from the positive terminal to the negative
What is the formula for calculating V AVG with regards to a sine wave?
V Avg = V Peak x 0.636
What is the definition of a coloumb? and give an example of a formula
the quantity of electrcity passing through and electrical circtuit. 1 Coloumb = 1 ampere per second
Q = I x T
Give a formula for frequency with regards to sine wave
Frequency = 1 / Time
