Electromagnetism and Transformers Flashcards
(12 cards)
1
Q
Loudspeaker
A
- Current carrying wire produces magnetic field
- magnetic field of wire interacts with magnetic field of magnet
- produces a force on teh wire
- produces a force on the cone
- Alternating current switches direction of magnetic field
- direction of force switches
- cone vibrates
- sound waves produced
2
Q
Flemmings Left Hand Rule
A
Thumb = Force
Finger = Direction of magnetic field
Middle Finger = current
3
Q
Construction of an Electromagnet
A
- Wrap wire into coil
- Place and iron core throguh the middle of coil
- Pass a current throguh the wire
4
Q
Only a force on a charged particle….
A
when it moves perpindicular through a magnetic field
5
Q
Increase size of induced voltage
A
- move conductor throguh field lines quicker
- Increase strength of magnetic field
- INcrease number of turns of coil
6
Q
Increase force on wire
A
- Increase current
- Increase strength of magnetic field
- Increase number of turns of coil
7
Q
Uniformed Magnetic Field
A
- Parrallel lines
- Evenly spaced
- Same direction
- Same strength at all points
8
Q
How does a transformer work
A
- steps up or steps down voltage
- AC in primary coil produces a changing magnetic field
- creates a changing magnetic field in the core
- core strengthens the magnetic field
- iron is a sfot material - easily magnetised/demagnetised
- field lines cut secondary coil
- induces a voltage in secondary coil
9
Q
Step-Up Transformer
A
- Increases number of turns in secondary coil
- Increases induced voltage in secondary coil
10
Q
Step-Down Transformer
A
- Decreases number of turns in secondary coil
- Decreases induced voltage in secondary coil
11
Q
Transformers in large-scale energy production
A
- Step up transformer transfer electrical energy from power station to national grid
- Step down transformer transfers electrical energy from national grid to homes
- Voltage is reduced to 230V so it is more useful and safer to use
12
Q
Input power = output power
A
100% efficiency
