electromagnetism Flashcards
(16 cards)
Factors that affect the size of the induced voltage:
Speed of rotation — faster spin = greater rate of change of magnetic field = larger voltage
Strength of the magnetic field — stronger magnet = more field lines = larger voltage
Number of turns on the coil — more loops = more voltage induced overall
Area of the coil — bigger coil = more field lines cut = larger voltage
Generating Electricity by Electromagnetic Induction
( 2 ways?)
Rotating a magnet inside a coil of wire
Rotating a coil of wire inside a magnetic field
Rotating a coil of wire inside a magnetic field
he coil cuts through magnetic field lines as it turns.
This also induces a voltage (and current, if in a closed circuit).
Rotating a magnet inside a coil of wire
As the magnet spins, the magnetic field through the coil changes.
This induces a voltage across the ends of the coil.
If the coil is part of a closed circuit, a current flows.
A voltage is induced in a conductor or coil when: (2)
It moves through a magnetic field, or
The magnetic field around it changes
process of voltage being induced?
Moving a wire through a magnetic field cuts through magnetic field lines.
This induces a voltage (and a current if there’s a complete circuit).
You can also induce a voltage by changing the magnetic field near a coil (e.g. moving a magnet in/out of a coil).
force acting on a wire depends on (3)Magnitude of the current
Magnitude of the current
Magnitude of the magnetic field
Direction of current or magnetic field
how does a loudspeaker work
The a.c. causes the current in the coil to constantly change direction.
This coil is in a magnetic field → Motor effect applies:
A force is exerted on the coil due to the magnetic field and current.
Since the current keeps changing, the direction of the force also changes.
This causes the coil (and attached cone) to vibrate back and forth.
These vibrations cause pressure variations in the air = sound waves.
how does a dc motor work
Current flows through the coil → sides of the coil are in a magnetic field.
The Motor Effect causes opposite forces on the two sides of the coil:
One side experiences an upward force, the other side a downward force.
This makes the coil rotate.
the split ring commutator reverses the direction of the current in the coil every half-turn.
This means the forces on each side of the coil stay in the same direction.
So the coil keeps turning in one continuous direction.
what happens when an electric current flows through a wire
a magnetic field is created
what does winding a wire into a coil do
strenthens the msgnetic field
how is an electromagnet formed
winding a coil of insulated wire, called a solenoid, around a core of magnetic material like iron. When an electric current flows through the wire, it creates a magnetic field that magnetizes the iron core, making the electromagnet strong.
what can be done to increase the strength of an electromagnet
increase number of coils
increase current
how can the field direction be reversed
by switching the current direction
when a charged particle moves in a magnetic field, as ling as its motion isn’t parallel, it
experiences a force
Why a force is exerted on a current-carrying wire in a magnetic field
when both magnetic fields interact, a force acts on them which moves the wire
