# Electromagnetic Induction

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The change in a magnetic environment surrounding a coil of wire will cause an EMF to be produced.
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Lenz's Law.
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It enhances Faraday's Law, adding to it that any induced EMF will act to oppose the change that caused it. Mathematically, this is represented by the negative sign.
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In Faraday's Law, what do the terms 'Nϕ' represent?
The term N represents the number of coils in the wire; the term ϕ represents magnetic flux (B x A). When multiplied, they represent 'flux linkage'.
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Explain the 'Corkscrew' effect in relation to a wire carrying an electrical current.
The corkscrew model predicts which way the magnetic field around a wire will orientate itself if that wire carries a current; If the wire is travelling away, the field is clockwise. Converse is true.
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If two wires carrying a current in the same direction are parallel, what happens? Why does this happen?
The field lines intersect causing a force to act between the two wires, pulling them towards one another.
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State the difference between: Magnetic Flux Density, Magnetic Flux, Flux Linkage
A) Magnetic flux density is a synonym for magnetic field strength, it is simply the MFS at a point in the field. B) Magnetic flux is the MFS across a cross-sectional area C) Flux Linkage is magnetic flux across a coil of wire.
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What is the unit of: A) Magnetic Flux Density? B) Magnetic Flux?
A) Symbol B, Unit Tesla (T), Base Units:kgs-2A-1 B) Symbol Φ, Unit Webber (Wb), Base Units: kg m2 s-2 A-1
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Explain Fleming's Left Hand Rule.
Fleming's Left Hand Rule allows you to predict which way a force will act on a wire carrying a current, in a magnetic field. When perpendicular to one another, the thumb, index finger and middle finger represent 'F', 'B' and 'I' respectively.
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How does a basic EM motor work?
A motor contains an axel carrying an electrical current that is allowed to rotate. When placed in an magnetic field, it begins to rotate (predicted by FLHR).
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What equation predicts the force on a current-carrying wire in a magnetic field?
F = BILsinθ (recall sin90 = 1) - L is the length of wire IN the magnetic field.
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What equation could you use to predict the force exerted on a charge travelling through a magnetic field?
F = Bqv (provided it is perpendicular to the field)
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What is conventional current?
Conventional current (incorrectly) assumes that charge flows out of the positive and towards the negative terminals (alternatively from positive to negative sources).
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Flemings Left Hand Rule could be used to predict the deflection of a proton in a magnetic field, true or false?
True.
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Magnetic/electric fields are vector quantities, true or false?
True. They have direction, therefore they are vector quantities.
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## Other cards in this set

Lenz's Law.

### Card 3

#### Back ### Card 4

#### Front

In Faraday's Law, what do the terms 'Nϕ' represent?

#### Back ### Card 5

#### Front

Explain the 'Corkscrew' effect in relation to a wire carrying an electrical current.

#### Back 