Topic 1: DC Basics Flashcards
(21 cards)
Charge
What is Charge measured in ?
Coulombs, Q or q
Charge
Define Charge
Quantity of electricity. Charge is Conservative i.e. cannot be created or destroyed
Charge
What is the electrical Charge of an Electron ?
The small and constant quantity of NEGATIVE electricity in an electron is 1.602x10(-19) Q
Charge
What is a Charged Atom defined as.
An Ion
Charge
Electron Accumulation means…
A negative charge of -q coulombs
Charge
Electron Depletion means…
A positive charge of q coulombs
Current
What is Current measured in?
Amperes, I or i
Current
Define Current
The rate of movement of charge through a circuit
Current
State the relationship between electrical current and time
Q = It ( 1 amp = 1 coulomb per sec)
Charge
How many electrons does a coulomb possess
6.24x10(18) electrons
Current
What is the Current of an Amp
6.24x10(18) electrons/sec
Voltage
What is voltage measured in?
Volts, V or v
Voltage
Define Voltage
Voltage or potential difference may be defined as the energy required to move a unit of charge from one point to another
shown as; V = dw/dq
where w is energy
Voltage
What is 1 volt equivalent to?
1 volt = 1 Joule/coulomb
Voltage
Describe the Current and Voltage relationship
I = Q/t therefore;
W = VQ = VI x t
Ohm’s Law
State the Equation for ohm’s law
V = IR
Electrical Energy
What happens when current flows in a resistant circuit ? Provide the equation that represents this.
Energy is Consumed
W = I^2xRxt ( Joules )
Joules = Watts/second
Electrical Energy
kWh is used commercially, what is 1 kWh in Joules?
1kWh = 1kW x h = 1000W x (60 x 60 )s = 3600000J = 3.6 MJ
Electrical Power
What is Power measured in?
Watts, P
Electrical Power
Define Electrical Power then describe the relationship between Power Energy and Time displaying the relevant equation(s).
Rate of Work Done
P = energy/time = ( I^2 x R x t)/t = I^2 x R
rearranging gives; P = VI
Kirchoff’s Current Law
State one rule of Kirchoff’s Law
the sum of currents entering a point/junction is zero
entering a point - positive
leaving a point - negative
