What happens when a magnet moves in a coil?
A Pd is induced
What happens if a magnet moves in a coil and is connected to a complete circuit?
A Pd is induced and a current will flow
What happens when a magnet is pulled out of the coil when a current is flowing?
Current flows in the opposite direction as to when it is pushed in
What is required for a current to flow in a coil?
Magnetic field strength through the centre must increase or decrease
What happens if the relative speed of the coil and the magnetic increases?
Induced voltage increases
What is induced potential?
If an electrical conductor moves relative to a magnetic field or if there is a change in the magnetic field around à conductor, a potential difference is induced across the conductor.
What is the generator effect?
If an electrical conductor moves relative to a magnetic field or if there is a change in the magnetic field around à conductor, a potential difference is induced across the conductor.
IF THE CONDUCTOR IS PART OF COMPLETE CIRCUIT, À CURRENT IS INDUCED IN THE CONDUCTOR. GENERATOR EFFECT
How do you induce a higher voltage in the generator effect?
Move faster
More coils
Stronger magnet
How to change the current direction?
Switch the magnetic poles
Move magnet in opposite direction
Alternator AC has … rings
Complete
Dynamo (DC) has … rings
Slip
Type of current for alternator
AC
Type of current for dynamo
DC
Not constant but always positive
How does the bulb light when the coil is rotated?
When it is rotated it cuts through the magnetic field lines of the permanent magnet
This induces à voltage across the coil
When the coil is connected to an external circuits current flows in the circuit and the bulb lights
Describe the structure of a generator:
When a magnet moves in a coil, à Pd is indcued- if connected to a complete circuit à current will flow
How to deliver electricity via the national grid?
Power station
Step up transformer
Cables and pylons (high voltage transmission lines)
Step down transformer
Homes/consumers
Voltage in power stations
25000 V
Step up transformer voltage
132-400 kV
Step down transformer voltage
230 V
What is the national grid?
Step up and step down transformer and high voltage transmission lines
What does a step up transformer do?
Increase voltage
Purpose of step up transfomers
Minimise energy loss as less energy is lost in cable when Pd is high due to resistive heating.
Reduces the current by increasing the voltage to reduce the dissipated power
Power wasted =
I (current) SQUARED x R (resistance)
What does the step down transformer do?
Decrease voltage
