Electromagnetic Induction (Edexcel IGCSE Science (Double Award): Physics): Flashcards
Exam code: 4SD0
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What is electromagnetic induction?
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What is electromagnetic induction?
Electromagnetic induction is the effect of inducing e.m.f. in a conductor due to the relative motion between a conductor and a magnetic field.
How can a voltage be induced in a wire?
A voltage can be induced in a wire by moving it through a magnetic field.
True or False?
A voltage can only be induced by moving a conductor in a magnetic field.
False.
A voltage can also be induced by placing a stationary conductor in a changing magnetic field.
How can the direction of an induced voltage be reversed?
The direction of an induced e.m.f. can be reversed by:
Reversing the direction of motion (of the magnet or conductor)
Swapping the poles of the magnet
True or False?
When the north pole of a bar magnet is pushed towards a coil, the end of the coil begins to act as a south pole.
False.
When the north pole of a bar magnet is pushed towards a coil, the end of the coil begins to act as a north pole.
As a result, the two like poles repel in order to oppose the motion of the magnet.
State the factors that will affect the size of the induced potential difference in the wire in the diagram.
The size of the induced potential difference in the wire in the diagram is determined by:
The speed at which the wire is moved
The strength of the magnetic field
State the factors that will affect the size of the induced potential difference in the coil in the diagram.
The size of the induced potential difference in the coil in the diagram is determined by:
The speed at which the magnet is moved
The strength of the magnetic field
The number of turns on the coils of wire
The size of the coils
The strength of the magnetic field
What is an A.C. generator?
An A.C. generator is a device which converts energy from a mechanical store to an electrical store.
What is the output of an A.C. generator?
The output of an A.C. generator is alternating current.
What components make up a simple A.C. generator?
A simple A.C. generator consists of:
A rectangular coil of wire rotating in a magnetic field
Slip rings and brushes
What is the purpose of the slip rings?
The purpose of slip rings is to provide a connection between the rotating coil and the external circuit.
How often does the direction of the current reverse as an A.C. generator rotates?
The direction of the current reverses every half rotation of the coil in the A.C. generator.
True or False?
A maximum value of current is induced when the coil is parallel to the magnetic field.
False.
A maximum value of current is induced when the coil is perpendicular to the magnetic field.
True or False?
There is a point in the rotation of the coil where no current is induced.
True.
No current is induced when the coil is parallel to the field.
What is the shape of the graph of output current against time for an A.C. generator?
For an A.C. generator, the shape of the graph of output current against time is a sine or cosine curve.
What is the frequency of an A.C. output?
The frequency of an A.C. output is the number of complete cycles it makes each second e.g. 1 cycle per second = 1 Hz.
How can the size of the induced current be increased in an A.C. generator?
In an A.C. generator, the size of the induced current can be increased by:
adding more turns to the coil
rotating the coil faster
increasing the strength of the magnet
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