Generating electricity Flashcards
Electromagnetic induction
electromagnetic induction is the production of an electromotive force (EMF) due to the change in magnetic flux through a conducting loop
electromotive force (EMF)
The voltage created or supplied due to energy being transformed into electrical potential energy
Magnetic flux
magnetic flux a measure of the amount of magnetic field lines passing through an area
Magnetic flux density
magnetic flux density is the amount of magnetic flux per unit area. Equivalent to magnetic field strength
Induced current
the induced current is the current produced in a conductor due to a changing magnetic field
AC (alternating current)
AC (alternating current) electricity is electricity with a periodically alternating direction of current and voltage
Alternator
Alternator a device that transforms kinetic energy into AC electricity by electromagnetic induction; an AC generator
Amplitude
amplitude is the magnitude of the maximum variation of any quantity with a changing value
DC (direct current electricity)
DC (direct current) electricity is electricity with a constant direction of current and voltage
Frequency
frequency is the number of cycles completed per unit of time
Generator
A generator is a device that transforms kinetic energy into (either AC or DC) electricity by electromagnetic induction
Period
period is the time taken to complete one cycle
Slip rings
slip rings s a component used to maintain a constant electrical connection between a stationary external circuit and a rotating coil
Slip ring commutator
A split ring commutator is a component used to reverse the electrical connection between a stationary external circuit and a rotating coil every half rotation
What is the formula to calculate magnetic flux when the magnetic field is perpendicular to the area
What is the effect of the angle between the magnetic field and the magnetic flux?
Magnetic flux is a maximum when the given area is perpendicular to the magnetic field.
When the area is not perpendicular, the effective area is reduced because fewer magnetic field lines pass through it.
If the area is parallel to the magnetic field, the effective area is zero so the magnetic flux will be zero.
Faraday’s law
States that a changing magnetic flux in a conducting loop or coil induces an electromotive force (equivalent to a voltage) with a magnitude that is proportional to the rate of change of the magnetic flux.
What is the formula to find the electromotive force (EMF)?
What does the negative sign in faradays law indicate?
The negative sign in Faraday’s law indicates the direction of the induced EMF and current. which can be disregarded in VCE physics
What can be found from Magnetic flux vs time graphs (Ø vs t) and EMF vs time graphs
The EMF is equal to n x the gradient of the graph.
The EMF graph should be negative when the magnetic flux graph has a positive gradient and vice versa.
Lenz Law
Lenz’s law states that when a conductor experiences a change in magnetic flux, a current will be induced such that its magnetic field acts to oppose the initial change in magnetic flux.
How do identify the flux through a loop?
- the area of the loop within the magnetic field is increasing or decreasing.
- the strength of the magnetic field within the loop is increasing or decreasing.
What does Lenz law state?
an induced current will flow in a direction such that the magnetic field created by the current will oppose the change in flux that induced the current.
The four steps involved determining the direction of the induced current.
- Identify whether the magnetic flux is increasing or decreasing.
- Identify the direction of the current
- Identify the direction of the induced magnetic field
4 Apply the right-hand coil rule, with the thumb pointing in the direction of the induced magnetic field identified in step 3, to determine the direction of the induced current.
