ENERGY MATTERS; Source To Consumer Flashcards
What is the size of voltage dependant on?
The number of turns of wire on the coil.
The strength of the magnetic field.
The speed of movement(the faster the coil is moved up and down through the magnetic field the greater the voltage).
How can voltage be produced? (Induced voltage)
When a wire is moved through a magnetic field or if the conductor remains stationary and the magnetic field changes.
What is the energy change in a dc motor?
Electrical to kinetic
What is the energy change in an ac motor?
Kinetic to electrical
Give two other names for ac motors
Dynamo or fenarator
What is a dynamo called an alternating motor?
Because an alternating current is produced.
What are the parts of a dynamo?
A rotor(electromagnets), stator (coils of wire) and a brush
In a full sized ac motor instead of permanent magnets it uses rotating electromagnets called a ______.
In a full sized ac motor instead of permanent magnets it uses rotating electromagnets called a rotor
What is the differnece between a full sized ac motor and smaller ac motor?
Commercial uses electromagnets to produce stronger magnetic field
The stator coil consists of several coils generate large current.
What are transformers used for?
To change size of ac voltage
Why are transformers used in transmitting electrical energy to homes?
To reduce power loss.
How do transformers reduced power loss?
They reduced current by increasing voltage
Why should current and resistance be kept low in power lines?
p=I*2R which shows they are related to power and should both be kept as low as possible.
What does a transformer look like?
Two wires of coil (primary and secondary) wrapped around a soft iron core.
What does the iron core do?
Concentrates the magnetic field.
How is a voltage produced in a transformer?
Current produces a magnetic field in the primary coil. Magnetic field rapidly builds up through bot sets of coils since they are joined by the iron core, this gives a changing magnetic field in secondary coil so a voltage is produced.
Step up transformers are used to _____ the voltage.
Increase
Step down transformers are used to _____ the voltage,
Decrease
A step up transformer has _____ turns on the secondary coil compared to the primary coil.
More
A step down transformer has _____ turns on the secondary coil compared to the primary coil.
Less
Give equation for relationship between number of turns and voltages
Ns/Np = Vs/Vp
For an ideal transformer primary power =
Secondary power
Therefore in an ideal transformer (voltage, no of turns current relationship)
Vs/Vp = Ns/Np = Ip/Is
Why is there energy loss in real transformers?
Heat loss as coils have resistance
Iron core continuously magnetised and demagnetised so heat procured
Vibrates due to magnetisation/demagnetisation so energy lost as sound
Some of the magnetic file produced leaks form Enron core so does not pass to secondary.
