Transcript ho do we get electricity

How do we get Electricity
How do we get Electricity
What is Electricity?
Electricity is energy transported by
the motion of electrons
**We do not make electricity, we
CONVERT other energy sources into
electrical energy**
Conversion is the name of the game
AC
• Alternating Current
– Large-scale generators
produce AC
– Follows sine wave with
n cycles per second
– 1, 2, 3-phase?
– US:120 V,60 Hz
– Malaysia: 240 V,50Hz
– Transforming ability
DC
• Direct Current
– Batteries, Photovoltaics,
fuel cells, small DC
generators
– Charge in ONE direction
– Negative, Positive
terminals
– Easy conversion AC to
DC, not DC to AC
Faraday Effect
• Faraday Effect
• Basic Concepts
• Voltage – V – Potential to Move Charge (volts)
• Current – I – Charge Movement (amperes or amps)
• Resistance – R – V = IxR (R in =ohms)
• Power – P = IxV = I2xR (watts)
Electric Motor
Electrical
Energy
M
Mechanical
Energy
DC Motor
Model Electric Motor
What do you need?
1.
2.
3.
Electric Energy
Coil
Magnetic Field
Flemming’s Left Hand Rule
(Motor Rule)
• Use: To determine the direction of a force
on a current carrying conductor in a
magnetic field
• The carbon rod is NOT magnetic.
• When no current flows, the rod is stationary
• When we turn on the current, the rod
experiences a force that makes it move.
• The direction of the force is determined by
Fleming' Left Hand Rule
Basic Theory
B
I
I
w
shaft
h
Next slide looks
down the shaft
Basic Theory
B
Current
coming
toward you
Shaft
Current
leaving away
from you
Basic Theory
B
direction by right-hand rule
Thumb = current
Forefinger = B
Rest = Force
F
F
T = 2hFcos
= 2hIwBNcos
Basic Theory
B
Basic Theory
B
Basic Theory
B
Basic Theory
B
Basic Theory
B
Basic Theory
B
Basic Theory
B
Basic Theory
B
Basic Theory
B
DC Motor
Electric Generator
Mechanical
Energy
G
Stationary magnets - rotating magnets - electromagnets
Electrical
Energy
Fleming’s Right hand rule
(Generator Rule)
• Use: To determine the direction of the
induced emf/current of a conductor moving
in a magnetic field.
•
Electromechanical Energy Conversion
Motor
Electrical
Energy
Mechanical
Energy
Generator
DEMO