Electromagnetism Flashcards
Are magnetic forces contact or non-contact?
Non-contact
What is a magnet?
An object capable of exerting a magnetic force.
What is the difference between a permanent and an induced magnet?
Permanent is always magnetic whilst induced only becomes a magnet when it’s in a magnetic field. Induced can only attract.
Describe magnetic field lines?
They point from the North Pole to the South Pole and don’t cross each other. It is strongest where they are closest.
What is the Earth’s magnetic field caused by?
The iron and nickel core.
What is a magnetic field?
Area surrounding a magnet that can exert a force on magnetic materials.
What is a solenoid?
A coil of wire carrying an electrical current - its shape causes a stronger magnetic field.
What does an electromagnet consist of? What is an example of where they are used?
A solenoid with an iron core.
An electric door bell.
What is Flemings left hand rule used for?
To find the direction of a force on a conductor in a magnetic field.
Fleming’s left hand rule:
Thumb
Forefinger
Second finger
Thumb - movement
Forefinger - field
Second finger - current
What is a dc motor?
An electrical device that uses direct current to produce a turning effect.
What is a split ring commutator’s purpose?
To keep the motor rotating in the same direction by allowing the current in the coil to change direction each half-turn as the coil rotates.
What will increase the strength of the magnetic field around a wire carrying a current?
Increasing the current.
What is the effect of putting an iron core inside a solenoid?
The electromagnet becomes stronger.
What are poles?
Ends of a magnet where the magnetic forces are strongest.