Download - T 01 electricity
ElectricityAndrew Wallace
Overview Electricity Units AC/DC
Height - potential Flow - current Width - resistance
Electricity Voltage (EMF) – height
V in Volts Current – flow
I in (milli) amps Resistance – width
R in Ohms (W) Controlling the Flow
Controlling the Flow U = IR U = voltage I = current R = Resistance Ohms Law
Example : I = 10 mA and R = 1 kW U = 10 mA * 1 kW = 10 V
Controlling the Flow Resistors
Wire Carbon Power rating Value – colour rings
Units What sizes do we use to measure
things? Nano - n Micro - m Milli - m Killo - k Mega - M
UnitsT G M k …, m m n p
12 9 6 3 -3 -6 -9 -12
Voltage Direct Current (DC) Alternating Current (AC)
Voltage Direct current
Flow Batteries
cells DC generators
Voltage Alternating
current Flow AC Generators Circles, triangles
and waves!
Voltage
Voltage
amplitude
Wave length
Voltage How many wave lengths do we have
each second? Herts (Hz)
F = 1/t
F = 300 / wave length (l) in MHz
Power How much work can we do?
Power (P) Current Voltage Watts (W)
P = IU
Power I = 2 mA U = 5 V P = IU = 2 mA * 5 V = 0.01 W
P = 5 W U = 24 V I = P / U = 5 W / 24 V = 0.208 A
Questions?