7 - Magnetic Fields Flashcards
(10 cards)
What is Fleming’s Right Hand rule?
Hold the right hand in a thumbs-up shape.
For a long, straight, current carrying conductor (a wire):
Thumb - Direction of current
Fingers - Direction of field
For a circular wire (solenoid, flat coil, electromagnet):
Thumb - Direction of field through the middle
Fingers - Direction of current in circle
What is Fleming’s Left Hand rule?
Thumb - Thorce
First Finger - Field (north to south)
Second Finger - Current (conventional current, positive terminal to negative terminal)
How are the field lines around a straight, current-carrying wire drawn?
Concentric circles, in a plane perpendicular to the direction of current in the wire.
To show the force being weaker further from the wire, the circles are further apart, further out.
How are the field lines drawn through a solenoid/electromagnet/flat coil?
Moving through the coil from the south end to the north, close together inside the coil to show the greater field strength, and further apart outside of it.
What are the general rules for drawing magnetic field lines?
Lines can never join, touch, or intersect.
Field lines are the direction in which the force occurs for an object feeling the force of the field.
Lines are drawn from north pole to south pole.
Stronger force means the lines are drawn closer together.
How are the north and south poles of a magnet defined?
The north pole is where the field lines exit the magnet, and the south pole is where they enter it.
For a pair of current-carrying, long, and straight conductors (wires), how do their fields interact?
The fields are forces - the forces add together, and the overall field around them is drawn from the resultants of the forces interacting.
For two parallel wires with current moving towards the viewer, what do the field lines around them look like?
Moving anti-clockwise around each wire, and both wires.
Empty spot of no force between the two wires, as the force from each cancels out.
Strongest force where forces from each wire are in the same direction.
Also, the wires will be pulled together in this configuration.
For two parallel wires, one with current moving towards the viewer and one moving away, what do the surrounding field lines look like?
Circles around the wires, given by the right hand rule.
The lines are in the same direction between the wires, so strongest there.
Also, the wires will be pushed apart in this configuration.
What is the experiment for proving F = B x I x l?
