Magnetism and Electromagnetism Flashcards
How do the different poles of the magnet interact?
like poles repel, unlike poles attract each other
What is a permanent magnet?
a magnet that can produce its own field and will repel and attract other magnets when in contact
cannot be demagnetised
What is a hard magnetic material?
a material that is magnetised when an external field is applied and stays magnetised when the field is removed
What is a soft magnetic material?
a material that is magnetised by an external field but get demagnetised when the field is removed
What is a magnetic field?
a region surrounding a magnet where other magnets will experience a force
Which direction do field lines in a magnetic field point?
From north to south
Does a high concentration of field lines mean the field is strong or weak?
strong
What must happen for a magnetic field to be created around a wire?
Current must flow though it
When current flows through a wire it induces a magnetic field
How do you use fleming’s left hand rule?
Force = thumb
Magnetic field = index
Current = second finger
How do you incerease the magnitude of the force acting on a current-carrying wire inside a magnetic field?
increases size of the current
increases the strength of the magnetic field
What is the motor effect?
When a current carryign wire is placed in a magentic field and experiences a force that pushes the wire
How is electrical current produced on a large scale?
an electromagnet is rotated around a coil
What affects the size of an induced voltage?
number of turns in the coil
the strength of the magnetic field
how fast the magnet moves
How does a dynamo generate current?
a coil of wire rotates inside a magnetic field
a commutator is used to ensure it rotates in the same direction
this keeps the current flowing in the same direction (D.C current)
How is electromagnetic induction used in alternators to generate alternating current?
a coil of wire rotates in a magnetic field
the end of the coil is connected to slip rings which will cause the current to change direction while rotating
this means a.c is produced
