P3.3 Flashcards
What do electric currents produce
Magnetic fields
What can forces produced in magnetic fields be used for
To make things move
What dont many appliances use
230 volts mains electricity
Why are transformers used
To provide the required potential difference
2 examples of transformers
Mobile phone chargers
Power supplies for laptop computers
What happens when a current flows through a wire
A magnetic field is produced around the wire
Example of electromagnets in use
On cranes for lifting iron or steel
How can the size of the force be increased
By increasing the strength of the magnetic field
Increasing the size of the current
When will a conductor not experience a force
When it is parallel to the magnetic field
When is the direction of the force reversed
When either the direction the direction of the current or the direction of the magnetic field is reversed
What happens if an electrical current ‘cuts’ through a magnetic field
It causes a potential difference across the ends of the conductor
What happens if a magnet is moved into a coil of wire
It causes a potential difference across the ends of the coil
What does an alternating current in the primary coil produce
A changing magnetic field in the iron core and therefore in the secondary. This causes an alternating potential difference across the ends of the secondary coil
In a step-up transformer the potential difference across the secondary coil is ….
Greater than the potential difference across the primary coil
In a step down transformer the potential difference across the secondary wire is….
Less than the potential difference across the primary coil
