Electromagnetism Flashcards
(20 cards)
What does the right hand thumb rule show?
-The thumb shows the direction of the current
-The direction of the rest of the fingers shows the magnetic field lines
What are the factors that affect the field strength?
-The size of current
-The distance from the conductor
What is the motor effect?
A wire with a current flowing through it is placed in a magnetic field and experinces a force
Why would a coil rotate in a motor?
-The side with the positive terminal would experience a downwards force
-The other side with the negative terminal would experience an upwards force
-This unbalanced force would cause rotation
Why do you need a split ring?
To allow 360 rotation in the coil
How does a split ring work?
-By swapping the positive and negative connections every half a turn
-So the forces acting on the coils would be acting in the same direction
What does Flemmings left hand rule show?
-The thumb is the direction of force
-The index is the magnetic field
-The middle finger is the current
What are the factors affecting the motor?
-the speed
-The direction of rotation
-the force
How could you change the speed of the motor?
-Increasing the current
-Increasing the strength of the magnetic field
How could you change the direction of rotation of the motor?
-Reversing the direction of the current
-Reversing the direction of the magnetic field by reversing the poles
How could you change the force of the motor?
-Increasing the current of the coil
-Increasing the strength of the magnetic field
-Adding more turns to the coil
What is electromagnetic induction?
When a voltage is induced in a conductor or a coil when it moves through a magnetic field or when a magnetic field changes through it
How is voltage induced?
-When a coil of wire moves into a magnetic field
-When a magnet moves into a coil of wire
What are the factors that affect the voltage?
-The magnetic field strength
-The speed of movement
-The amount of turns in a coil
-The size of the coils
How does a stronger magnet affect the voltage?
-A stronger magnet leads to a stronger magnetic field
-A stronger magentic field leads to a larger voltage
How does the speed of movement affect the voltage?
-The quicker the wire or magnets move, the faster the magnetic field will change
-Which leads to higher potential difference (voltage)
How does the amount of turns in a coil affect the voltage?
-The more turns, the higher the potential difference (voltage)
-This is because each coil will cut through the magnetic field lines and the potential difference (voltage) will increase due more coils cutting the magnetic field
Describe how a headphone looks.
-There is a cone which has a coil of wire wrapped around one end
-The coil of wire is connected to an A.C electrical supply
-There is a permanent magnet that goes inside the cone and coil of wire
Describe how a heaphone works.
-As the current passes through the coil, it generates a magnetic field
-The magnetic field from the coil will now interact with the magnetic field from the permanent magnet
-This produces a resultant force which causes the cone to move
-When currents are switches, the direction of force reverses.
-Therefore the cone moves in and out, generating sound
How could you change the volume and pitch of headphones? Explain why
-By changing the frequency of the A.C. supply
-Doing this will change the frequency which the cone vibrates
- A higher frequency produces a higher pitch sound and vice versa
-You could also change the current’s size, increasing the vibration’s amplitude. Which increases volume
