Magnetism Magnetic Field Magnetism is a force of ___________ or ___________ that acts at a distance and is due to a _____________ field. Magnetic fields are caused by _____________ electrically charged particles. attraction repulsion magnetic moving Magnetic Field Just like electric fields, magnetic fields are represented by _________. Magnetic fields originate on _______ _________ and terminate on _______ _________ . Unlike electric charges, magnetic poles cannot be ___________. arrows north poles south poles isolated

µo I B = 2r Magnetic field around a current carrying wire Magnetic fields are caused by _____________ electrically charged particles. Thus any wire carrying _______________ will induce a __________ ________ around the wire. The shape of the magnetic field is ___________ __________. moving current magnetic field concentric circles Magnitude of the magnetic field around a current carrying wire µo I B = 2r Where: B = magnetic field strength (Tesla) µo = 4π x 10-7 T.m/A I = current (amperes) r = distance from the wire (meters)

Direction of the magnetic field around a current carrying wire Right Hand Rule I Thumb - points in direction of conventional current encompass the wire in the direction of the magnetic field Fingers - * The Right-Hand Rules apply to positive charges or positive (conventional) current

F = qvB Forces on moving charges When a charge is placed in an ____________ ___________ ________, that charge will experience a ____________ _________ if two conditions are met. external magnetic field magnetic force 1) the charge is moving relative to the magnetic field, 2) the charge's velocity has a component perpendicular to the direction of the magnetic field Magnitude of the force on a moving electric charge F = magnetic Force (N) F = qvB Where: q = electric charge (C) v = velocity of charge (m/s) B = EXTERNAL magnetic field (T)

F = Il B l = Magnitude of the force on a current-carrying wire magnetic Force (N) F = Il B Where: I = current (A) l = wire length (m) B = EXTERNAL magnetic field (T) Direction of the force on a moving charge or a current- carrying wire Right Hand Rule II Thumb - points in direction of conventional current points in the direction of the external magnetic field Fingers - Palm - points in the direction of the force I

Practice RHR I P Direction of B field? (a) I (b) Direction of B field at point P? B out of the page I (d) P Will wires attract or repel? (c) attract The field at point P is into the page, what direction is the current? I I

Practice RHR II - B N S In what direction is the proton deflected? X X X X X X X X N S In what direction is the proton deflected? out of the page + The wire is pulled down, which way is current induced? B left B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O - In what direction is the electron deflected? Which direction will the wire move? out of the page left

Try this mv r = qB B X X X X X X X X Where: In what direction is the charge initially forced when entering the field? B X X X X X X X X right What happens to the path of the charge as it moves through the field? mv r = qB It curves - Where: v = velocity of charge (m/s) q = charge (C) r = radius of curved path (meters) m = mass of charge (kg) B = EXTERNAL magnetic field (T)