Electrical Fundamentals Flashcards
How does static electricity occur?
The electrons from one item transfer to another item that is being contacted, then the two items are left with extra electrons and missing electrons.
What is the formula for resistance in a wire?
Resistance = ohms * (length of wire / cross section of wire)
What actions can electrical current bring about?
Chemical action, heat action, and magnetic action.
What is the rule which governs how the direction of magnetic flux flows around a wire?
Ampere’s rule of right-hand screw.
How does a solenoid work?
A solenoid uses electrical magnetism, by coiling a wire, to draw up a easily magnetised piece of metal.
How does a solenoid increase magnetism if coiling a wire doesn’t create enough magnetism?
If a iron core is put inside the solenoid, many more lines of magnetic flux are created and the magnetic strength increases substantially.
What are common conductor materials?
Gold, silver, copper, aluminium, or iron.
What are common semi-conductor materials?
Silicon and germanium.
What are common insulators?
Glass, rubber, paper, plastic, vinyl, or porcelain.
How do you work out total circuit resistance in a series circuit?
Add all the individual resistances together.
How do you work out the voltage drop of each resistance in a series circuit?
Multiply the circuit amperage by the individual resistance.
How do you work out the current flowing through each resistor of a parallel circuit?
Divide the circuit voltage by the resistor.
How do you work out total resistance in a parallel circuit with only two resistors?
(R1 * R2) / (R1 + R2)
What is the formula for working out total resistance in a parallel circuit with many resistors?
1/Rt = 1/R1 + 1/R2 + 1/R3 etc. (example: 1/Rt = 1/200 + 1/470 + 1/220 = 0.0117; therefore, Rt = 1/0.0117 = 85ohms)
What can be said about adding more resistors to a parallel circuit?
The more resistors that are added to a parallel circuit, the lower the total circuit resistance will be.
