Chaper 1 Basic DC review

What is an electric current

A flow of electric charge

Electric charge can be both ___ and ___ but usually consists of…

positive and negative charge carriers, negatively charged electrons

What are positive charge carriers called

holes

Does the positive or negative side act as the driving force?

The positive side acts as the driving force

What are the 3 basic equations for electrical power?

P=VI, P=I²R, P=V²/R

How would you determing the resistance of a componant using a graph?

Plot a V-I graph then 1/gradient

What is Kirchhoff’s voltage law?

The voltage supplied to a circuit must equal the sum of the voltage drops in the circuit

What is kirchhoffs current law?

The current flowing into a junction must be equal to the current flowing out of it

Derive the formula for V1(out)

Vout = Vin × R2/R1+R2

Derive the formula for I1(out)

Iout = Iin × R2/(R1+R2)

What is a time constant for a capacitor?

The time taken for the capacitor to charge to 63%

What are the two main types of capacitors?

Ceramic and electrolytic capacitors

What is the difference between ceramic and electrolytic capacitors?

Electrolytical - uses a conductive electrolytic fluid to act as one of the plates; the other plate is made of metal.

Electrolytic- uses an oxide as the insulating material

(also slightly different symbols)

how do u determing the capacitance of multiple capacitors?

The opposite to resistors

1.5 (current takes the path of least resistance)

How do you work out R2 for resistors in parallel when given Vs, R1 and I

Work out Rt, then do 1/Rt to get the required decimal. Next do 1/R1.

1/Rt - 1/R1 = (a number equivalent to a decimal which you 1/ to get the true value) (200)

What are the equations for capacitance?

The equations for capacitance are:

1. Capacitance (C) = Charge (Q) / Voltage (V)

2. (Capacitance (C) = Electric Field (E) * Area (A) / Distance (d)

3. Capacitance (C) = Permittivity of the material (ε) * Area (A) / Distance (d))

(prob only use the first one)

What is the equation for time constant (Capacitors)

T=RC

1.9V

How many time periods does it take to fully charge a capacitior?

Approximately 5

How do capacitors store charge?

Capacitors are made from 2 plates with an insulator inbetween. Electrons flow to one end of the plate causing it to become more negatively charged. Due to the elecectrons being unable to flow a negative charge builds up on one side. Although the electrons dont flow they still repel electrons from gathering on the other plate, creating a positive terminal.