Magnetic fields Flashcards
What is a magnetic field?
Force field surrounding a magnet or current-carrying acting wire that acts on any other magnetic or current-carrying wire placed in the field
WHat are north-seeking and south-seeking poles?
magnetic field of a bar magnet is strongest at the ends
difference between north and south, the free ends align itself withe horizontal component of the Earth’s magnetic field
What is the line of force?
magnetic field line
line along which a north pole would move in the field
What is the motor effect?
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
this effect is known as the motor effect
the force is perpendicular to the wire and to the lines of force
what does the magnitude of the force depend on?
current, strength of field, length of wire, angle between lines of force and current direction
When is the force greatest / when is it zero?
greaterst when the wire is at right angles to the magnetic field
zero when the wire is parallel to the magnetic field
What is Fleming’s left-hand rule?
direction of the force can be related tot he direction of the fiel and to the direction of the current using Fleming’s left hand rule
How is the magnitude of the force on a current-carrying wire in a magnetic field investigated?
stiff wire frame connected in series to switch, ammeter and variable resistor and battery
when switch is closed the magnet exerts a force on the wire which can be measured from the change of the top pan balance
propotional to current and length of wire
WHat is the magnetic flux density?
sometimes reffered to as strength of the field
defined as the force per unit length per unit current on a current-carrying conductor at right angles to the magnetic field lines
