# Magnetic fields

• Created by: argyrou
• Created on: 30-04-18 22:47
In a magnetic field which direction do the field lines go?
North to south
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Define magnetic field
Force field surrounding a magnet/current carrying wire placed in the field
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What is the motor effect?
When a current-carrying wire placed at a non-zero angle to the lines of force of an external magnetic field experiences a force due to the field,
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What are the 4 factors that the magnitude of a force is dependent on?
- current - strength of the magnetic field - length of the wire - angle between the lines of force of field and current direction
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When is force greatest/at a maximum?
When the wire is at right angles to the magnetic field
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What is magnetic flux density B in words?
Magnetic field strength.
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What equation combines flux densitly, current and legth of wire?
F=BIL
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F=BIL only applies when B and I are at right angles to each other. How would you adapt the equation if the wire was at an angle to the field?
F=BILsinX
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Define torque of a couple in words
When 2 forces are equal in magnitude but act in opposite directions
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How would you adapt F=BIL when its for a coil rather than a wire in a magnetic field?
F=BILn
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What is the simple equation for the torque of a couple?
torque of couple = Fd (d=perpendicular distance between line of action of forces on each side)
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What is the torque of a couple when the coil is at an angle within the field?
BIAncosX (where A=width x length and width comes from distance)
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Define conventional current in terms of electron movement
In opposite direction to the way in which electrons move
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How does flux density B, charge and voltage link?
F=BQV
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What equation would you use to find the radius of a charged particle in a circular orbit?
r=mv/BQ
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What are the speed of particles when they exit from a cyclatron?
v=BQR/m
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What is the equation to find the time period of a charged particle in a circular orbit?
T=2m /BQ
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## Other cards in this set

### Card 2

#### Front

Define magnetic field

#### Back

Force field surrounding a magnet/current carrying wire placed in the field

### Card 3

#### Front

What is the motor effect?

### Card 4

#### Front

What are the 4 factors that the magnitude of a force is dependent on?

### Card 5

#### Front

When is force greatest/at a maximum?