What Is Current
Electric current is a physical quantity that designates the rate that electric charge passes a point in a circuit
each second.
Current Formula
Q = It
Prefixes
M = Mega = 10^6
k = kilo = 10^3
m = milli = 10^-3
μ = micro = 10^-6
n = nano = 10^-9
What is Voltage?
Voltage is a physical quantity that tells us how much energy is transferred to 1 coulomb of charge as it
passes through a battery, cell or power supply.
Voltage Formula
E = VQ
What Is Resistance
Electrical Resistance is a quantity that determines how good a material is at insulating electrically, or
alternatively how poor a material is at conducting electricity.
Resistance formula
V = IR
What is Power?
the rate that energy is given to circuit element or taken from
a battery or power supply.
Power Formula
P = VI
When LDR Lit High/Low Resistance
Low
Formula for R_total in series
R_total = R_1+R_2+R_3
Formula for R_total Paralel
R_total = (R_1 * R_2) / (R_1 + R_2)
Direction of magnet
Into South Out of north
What is the right hand grip rule
right-hand
grip rule:
* The thumb indicates the direction of conventional current in the wire
* The fingers wrap around the wire in the direction of the magnetic field
What are the symbols for current flowing in and out of page (3d)
- × The cross represents movement into the page.
- ∙ The dot represents movement out of the page.
How to find direction of magnetic force (Right hand slap)
Right-hand slap rule:
* Thumb points in the direction of conventional current
* Fingers point in the direction of the magnetic field (North to South)
* Palm points in the direction of the magnetic force
Colour Coding of resistors
1st Colour Band
1st Digit
2nd Colour Band
2nd Digit
3rd Colour Band
Number of Zeroes
black 0
brown 1
red 2
orange 3
yellow 4
green 5
blue 6
violet 7
grey 8
white 9
How Does A Transistor Work
When current flows through the base current can flow from a collector to an emitter
Battery Symbol / Power Supply
short line and long line - Battery has + symbol and voltage
resistor Symbol
Rectangle with omes
LDR symbol
rectangle circle and arrows drawing in
Light Globe
Either circle with X or line with lump in circle
Capacitor
Two equal lines perpendicular to wire
LED
triangle then line in direction of current, arrows poining out
