MAGNETISM Flashcards
What does magnetic field do?
Magnetic field changes trajectory of a charged particle (field is related to a moving electric charge)
Which metals are naturally magnetic?
Iron, copper and nickel are natually magnetic at room temperature
Explain magnetic field lines and the relation of magnetic induction to them
Magnetic field lines are always closed curves which flow from the north to south pole of a magnet. Magnetic induction is tangent to magnetic filed lines.
What properties does Fleming’s left hand rule explain and relate?
Fleming’s left-hand rule explains a current-carrying wires interaction with an external magnetic field. It relates force, magnetic induction and current.
What trajectory will a charged particle moving in a magnetic field exhibit?
A curved trajectory (circular). Where Force is perpendicular to drift velocity and force is also perpendicular to the magnetic induction.
What does magnetic force change in a charged particle and what will happen with the greater velocity of the particle?
Magnetic force changes only the direction of particle not the magnitude of velocity. The greater velocity of a particle the greater the force that acts on it.
Force on a current carrying wire?
F = IlBsin(a)
How to find direction of magnetic field on a wire?
With Ampers right hand rule (Thumb is direction of current and fingers exhibit direction of magnetic field)
Does Earth have a magnetic field, if yes why?
Earth does have a magnetic field due to the moving current in the molten core. We can imagine a magnetic inside the earth with a north and south pole.
What does Biot-Savart law explain?
Magnetic intensity at any point due to a steady current in a straight wire
What does Ampere’s law state?
For any closed loop path, the sum of the length elements multiplied by the sum of the magnetic field in the direction of the length element is equal to the current in the wire multiplied by the magnetic permeability of a vacuum.
What are the three types of magnetic materials and their magnetic properties?
Diamagnetic materials: atoms are non-magnetic and has a magnetic susceptibility < 0
Paramagnetic materials: atoms are magnetic (Al, Li, Au) but are concealed but structure so they are weakly magnetic
Ferromagnetic materials: atoms are magnetic and structure allows magnetism (Fe, Cu, Ni)
Explain a solenoid and its magnetic properties
A solenoid is a coil of wire in cylindrical form with a number of turns. When carrying current, the inside of the coil has a homogenous magnetic field. Its magnetic intensity is given from Amperes law.
What are the magnetic properties of matter?
Moving electrons in atoms create small magnetic fields. Magnetisation, M, describes how much matter is magnetised (the density of permanent/induced magnetic dipole moments)
How can ferromagnetic materials be described graphically?
With the hysteresis loop. Magnetic induction, B on x-axis and magnetisation, M on y-axis. Shows magnetisation curve from demagnetised to magnetised and reverse of magnetic field.
