Physics 5.11 - 5.15 Flashcards
What is a fuse and how does it work?
A fuse is a small wire connected to the main. When a high current passes through the main circuit, it also passes through the fuse which will heat up and melt, breaking the circuit in order to prevent further damage, fuses have a set current to break at
What is a circuit breaker and how does it work
A circuit breaker is a device that breaks the circuit when the current is too high. The circuit breaker trips causing the circuit to break. Unlike fuses, circuit breakers can be easily reset instead of having to be replaced every time
What is earthing
Earthing is providing an alternate pathway for current to flow in the case of loose wiring to prevent people from getting shocked
What is double insulating
Double insulating is covering a conductive material with a non conductive material which prevents people from getting shocked in the case of a loose wire
How is a potential difference or a current induced on a wire and what do we call the process?
The process is called electromagnetic induction where a wire is passed through a magnetic field in a way that it goes or cuts through the magnetic field lines. This induces an alternating potential difference if the wire is open and an alternating current if the wire is closed
How can we increase the magnitude of this potential difference or current? (3 methods)
We can turn the wire into a coil with many turns
We can increase the strength of the magnetic field
We can pass the wire through the magnetic field faster
What are split ring commutators and in which generator are they used?
And how are the contacts placed?
Split ring commutators are two metal plates that are split in half. Each half is connected to one side of a circuit that is used in a dynamo
The contacts are placed near each piece of metal so it rubs the metal as the dynamo spins
What are slip rings and brushes
and which generator are they used in?
Slip rings are pieces of metals that form a complete loop, brushes are the contacts used for slip rings which are placed both on one side of the slip ring
It is used in an alternator
What type of current does a dynamo produce?
Direct current
What type of current does an alternator produce?
Alternating current
What happens to the amplitude and frequency when a dynamo or alternator spin faster
The amplitude and frequency increase
What is electromagnetism
Electromagnetism is when a wire carrying current creates its own magnetic field
What is an electromagnet
An electromagnet is a magnet created by current flowing through a wire
What is the right hand rule
The right hand rule is a rule used for finding the direction of the magnetic field in a wire based on the direction of the current
What is a solenoid
A solenoid is a wire with many turns
How do we find the north on an electromagnet solenoid
We find the north side of an electromagnet solenoid by looking at the point where current enters the wire
How do we change the direction of the magnetic field in a solenoid
By flipping the direction of current flowing through the solenoid
What happens to the solenoids magnetic field when the current is cut off?
The magnetic field disappears
Name 4 ways of increasing the strength of an electromagnetic solenoid
Increasing the current
Increasing the number of turns
Decreasing the space between each turn or compressing the solenoid
Adding an iron core to the solenoid
What is the motor effect
The motor effect is the force a current carrying wire experiences when in the presence of a magnetic field
Why does a current carrying wire experience a force in the presence of a magnetic field?
The current carrying wire becomes a magnet because current carrying wires generate their own magnetic fields and when two magnets interact, they can get attracted or repelled
At what angle does the current carrying wire experience the full force of the magnetic field
When it is perpendicular to the field lines
What is the formula of the force that current carrying wires experience and when is this formula applicable?
Formula = F = BIL where b = magnetic flux density or magnetic field strength (Teslas/T), I = current(amps). and L = length of wire in meters
it is applicable when the wire is perpendicular to the magnets magnetic field lines
How do we determine the direction of the force, the direction of the current, and the direction of the magnetic field lines?
We use flemmings left hand rule where your middle finger is the direction of current, thump = direction of force and pointer = direction of magnetic field lines
