Physics - Electromagnetism Flashcards
Which way does the magnetic field travel?
North to south
What is a uniform magnetic field?
When magnetic field lines are the same distance apart from each other, we say that the magnetic field is uniform.
What is magnetic flux density?
This is the amount of flux passing through an unit area at a right angle to the magnetic field lines. It is measured in Tesla (T).
How do you determine from above if wires with current are coming towards you or away from you ?
Towards - Circle with dot in the middle.
Away - Circle with cross in the middle.
What do the three fingers do in Fleming’s left hand rule?
-thuMb - Movement (force)
-Forefinger - Field (magnetic field)
-seCond finger - current
When is Fleming’s left hand rule used?
Use Fleming’s left-hand rule to remember the direction of motion in an electric motor.
What is the motor effect?
A current-carrying wire or coil can exert a force on a permanent magnet. This is called the motor effect.
What is the purpose of a split ring?
The direction of the current must be reversed every half turn, otherwise the coil comes to a halt again. This is achieved using a conducting ring split in two, called a split ring or commutator.
How is the induced voltage increased?
rotating the coil or magnet faster
using a magnet with a stronger magnetic field
having more turns of wire in the coil
having an iron core inside the coil
What is an alternating current and a direct current in a generator?
Alternating - In a generator, one side of a coil moves up during one half turn and then down during the next half turn. This means that as a coil is rotated in a magnetic field, the induced current reverses direction every half turn. This is called alternating current (a.c.).
Direct - It is different from the direct current (d.c.) produced by a battery, which is always in the same direction.
What is the difference between step up and step down transformers in terms of coils?
Step-up transformers have more turns on the secondary coil than they do on the primary coil.
Step-down transformers have fewer turns on the secondary coil than they do on the primary coil.
