Chp 4/5: Electrical Circuits Flashcards
Define the law of conservation of electric charge
electric charge cannot be created or destroyed and is always conserved. Therefore, if an object gains charge, it must lose an equal amount.
Define electrical potential difference
It measures the electrical potential energy per unit charge
Measured in volts
Found; W=VIt (work = pd x current x time)
or using V=W/q
Why does electric charge separation produce electrical potential difference?
In a circuit, the energy requires for charge separation is provided by the cell or battery. The chemical energy within the cell transforms into electrical potential energy. This means there is more electrical potential difference.
Define electric current
It is the flow of charge through a closed circuit carried by discrete charge carriers (electron or ions)
I=q/t
q= number or electrons x charge of one electron
Define resistance
A property of a substance that hinders current and converts electrical energy into other forms. Unit is ohms
Recall ohms law
V=IR
Potential difference = current x resistance
Define power
A measure of HOW MUCH energy is converted in a unit of time (s). Units is WATTS
P = VI or P = W/t
Define power dissipation
The process by which an electronic or electrical device produces heat (energy loss or waste) as an undesirable outcome of its primary action.
P = I^2 x R
Power = current^2 x resistance
Draw the following circuit components;
resistor, voltmeter, ammeter, cell, battery, switch, bulb
Refer to notes
Compare series and parallel circuits in relation to current, potential difference and total resistance around the circuit.
Current in a series circuit is : constant
Current in a parallel circuit is : shared
Potential Difference in a series circuit is : shared
Potential Difference in a parallel circuit is : constant
Total resistance in a series circuit is : Rt = R1 + R2 +….
Total Resistance in a parallel circuit is : 1/Rt = 1/R1 + 1/R2 +… (reciprocal)
Recall Kirchhoff’s current law
electric charge is conserved at all points in an electrical circuit
Recall Kirchhoff’s voltage law
energy inputs in a circuit equal the sum of energy output from loads in the circuit
What is the difference between conventional current and electron flow?
Conventional current or simply current, behaves as if positive charge carriers cause current flow. Conventional current flows from the positive terminal to the negative. Electrons flow from the negative terminal to the positive. This was discovered after CC and is the correct flow of electrical energy.
