When iron filings are placed in a magnetic field they form a pattern of lines called...
Magnetic field lines, or lines of force
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What is a magnetic field?
The region around a magnetic where a piece of iron or steel will be attracted to it.
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How does an electromagnet work?
An insulated wire is wrapped around an iron core. When an electrical current flows through the wire, a magnetic field is produced around the wire.When the current is switched off the iron loses its magnetism.
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What are some uses of electromagnets?
Circuit breakers, scrapyard cranes, electric bells, relays.
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What is the motor effect?
When a current carrying wire in a magnetic field, not parallel to the magnetic field lines, experiences a force from the magnetic field
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When is the force at its maximun on the wire?
At a 90 degree angle
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When is the force 0 ?
When the wire is parallel to the magnetic field.
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How can the size of the force be increased?
By increasing the strength of the magnetic field, and the size of the current
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How can the direction of the force acting on the wire be reversed?
By reversing the direction of current or magnetic field.
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Explain what Flemming's left hand rule is what each finger represents.
Flemming's left hand rule determines the direction of the force in the motor effect. The first finger represents the magnetic field from north to south. The second finger represents the direction of current. The thumb represents force's direction.
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How does an electric motor work?
A current passes through the coil, due to the motor effect a force acting upwards pushes the coil round a half time. The current is in the opposite direction on the other side of the coil and so a down force pushes the coil round another half turn.
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How can we increase the speed of an electric motor?
By increasing the size of the current
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How can reverse the direction of the motor?
Reverse the direction of the current.
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What is a split ring commutator?
A device that reverses the direction of the current around the coil every half turn. Because the sides swap over each half turn the coil is always pushed in the same direction.
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What is electromagnetic induction?
Electromagnetic induction is the process of creating a potential difference using a magnetic field.
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How is a potenital difference induced across the ends of an electrical conductor?
If an electrical conductor cuts through magnetic field lines a potential difference is induced because the electrons in the conductor experience a force.
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How can a current be produced from electromagnetic induction?
If the electrical conductor is apart of a complete circuit a current passes through it as the electrons are experiencing a force.
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What is potential difference?
Potential difference is the amount of work/energy required to move an electric charge from one point to another in a circuit. V = E/Q
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If i reverse the direction of the movement of the conductor/wire, and reverse the polarity of the magnet, what will happen to the induced potential difference?
It will be reversed.
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How can I increase the induced potential difference?
Increase the speed of movement, strength of magnetic field, number of turns of a coil.
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Other cards in this set
Card 2
Front
What is a magnetic field?
Back
The region around a magnetic where a piece of iron or steel will be attracted to it.
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