TV Magnetism (Lecture)
2/26/2014Magnets and Magnetic FieldsHowever, if you cut a magnet in half, you don’t get a northpole and a south pole – you get two smaller magnets.MagnetismLecture NotesMagnetism 20Magnetism 20Magnets and Magnetic FieldsChapter 20 TopicsMagnets and Magnetic FieldsElectric Currents Produce Magnetic FieldsForce on an Electric Current in a Magnetic FieldForce on Electric Charge Moving in a Magnetic FieldMagnetic Field Due to a Long Straight WireMagnetic fields can be visualized using magnetic field lines,which are always closed loops.Force between Two Parallel WiresSolenoids and ElectromagnetsMagnetism 20Magnets and Magnetic FieldsMagnetism 20Magnets and Magnetic FieldsMagnets have two ends – poles – called north and south.A uniform magnetic field is constant in magnitude anddirection.Like poles repel; unlike poles attract.The field between thesetwo wide poles is nearlyuniform.Magnetism 20Magnetism 201
2/26/2014Electric Currents Produce Magnetic FieldsForce on an Electric Current in a Magnetic FieldThe force on the wire depends on the current, the length ofthe wire, the magnetic field, and its orientation.Experiment shows that an electric current produces amagnetic field.F ILB sin θθLThe force is directedinto the screen.IBThis equation defines the magnetic field B.Unit of B: the tesla, T.1T 1NA mMagnetism 20Magnetism 20Force on an Electric Current in a Magnetic FieldElectric Currents Produce Magnetic FieldsThe force on the wire depends on the current, the length ofthe wire, the magnetic field, and its orientation.The direction of the field is given by a right-hand rule.F ILB sin θFWhen the current isperpendicular to themagnetic field.BIF ILBLMagnetism 20Force on an Electric Current in a Magnetic FieldMagnetism 20Force on an Electric Current in a Magnetic FieldProblem 20-04A 1.5-m length of wire carrying 4.5 A of current is orientedhorizontally. At that point on the Earth’s surface, the dipangle of the Earth’s magnetic field (5.5 x 10-5 T) makes anangle of 38 to the wire. Estimate the magnitude of themagnetic force on the wire due to the Earth’s magnetic fieldof at this point.A magnet exerts a force on a current-carrying wire. Thedirection of the force is given by a right-hand rule.F ILB sin θF (4.5 A ) (1.5 m )Be(5.5 x 10 5)T sin 38IθF 2.3 x 10 4 NMagnetism 20Magnetism 202
2/26/2014Force on an Electric Current in a Magnetic FieldProblem 20-08Suppose a straight 1.00-mm-diameter copper wire could just“float” horizontally in air because of the force due to the Earth’smagnetic field which is horizontal, perpendicular to the wire,and of magnitude What current would the wire carry?Problem 20-09Alpha particles of charge 2e and mass of 6.6 x 10 27 kg areemitted from a radioactive source at a speed of 6.6 x 107 m/s.What magnetic field strength would be required to bend theminto a circular path of radius of 0.25 m?ILBILBe mgBI d ILBe ρπ L g 2 2I Force on Electric Charge Moving in a Magnetic FieldmgBe 3 kg 3 8.9 x 10 2 π 1.0 x 10 m 2m g4 5.0 x 10 5 T(ρπd 2g4B e(mv 2FM qvB rvr))B mvqr(6.6 x 10 kg )(6.6 x 10 m/s ) 2(1.6 x 10 C ) (0.25 m ) 27 7 195.4TI 1400 AMagnetism 20Force on Electric Charge Moving in a Magnetic FieldBqThe force is directedout of the screen.Force on Electric Charge Moving in a Magnetic FieldProblem 20-10Determine the magnitude and direction of the force on anelectron traveling horizontally v 8750 m/s, to the east in avertically upward magnetic field of strength 0.75 T.northThe force on a moving charge in a magnetic field isrelated related to its charge and velocity.F qvB sin θMagnetism 20Direction?v θeastFM qvB(Once again, the direction is given by a right-hand rule.)()FM 1.6 x 10 19 C 8.75 x 10 3 m/s (0.75T )FM 1.05 x 10 15 NMagnetism 20Force on Electric Charge Moving in a Magnetic FieldIf a charged particle ismoving perpendicular to auniform magnetic field, itspath will be a circle.qvB qFmv 2rForce on Electric Charge Moving in a Magnetic FieldProblem 20-16FE vWhat is the velocity of a beam of electronsFMthat go undeflected when passing throughperpendicular electric and magnetic fields of3 3magnitude 8.8 x 10 V/m and 3.5 x 10 T,respectively? What is the radius of the electron orbit ifthe electric field is turned off?mv 2FM qvB FE FMrmvr qE qvBqBE 8.8 x 10 3 V/mv 9.11 x 10 31 kg 2.5 x 106 m/s B 3.5 x 10 3 T1.6 x 10 19 C 3.5 x 10 3 TvF qvBMagnetism 20BMomentumqrB mv((v 2.5 x 10 6 m/sMagnetism 20)()())r 4.1 x 10 3 mMagnetism 203
2/26/2014Magnetic Field Due to a Long Straight WireForce between Two Parallel WiresThe field is inversely proportional to the distance from thewire:prµ IB o2 πrThe magnetic field produced at theposition of wire 2 due to the currentin wire 1 is:µ IB1 o 12π dThe force this field exerts on a length Lof wire 2 is:F I 2 LB1I µ I F I1L o 1 2π d The constant µ0 is called the permeability of free space, andhas the value:µ o 4π x 10 7 T m/AF µo I1I 2 L 2π dMagnetism 20Magnetism 20Force between Two Parallel WiresMagnetic Field Due to a Long Straight WireProblem 20-26A jumper cable used to start a stalled vehicle carries a 65-Acurrent. How strong is the magnetic field 6.0 cm away fromit?pµo I4 π x10 7 T m/A (65 A )B 2 πr2π 6.0 x10 2 mr()(Parallel currents attract; anti-parallel currents repel.I1I2I1I2)B 2.2 x10 4 TIFF FFMagnetism 20Magnetism 20Magnetic Field Due to a Long Straight WireForce between Two Parallel WiresProblem 20-32A power line carries a current of 95 A along the topsof 8.5 m-high poles. What is the magnitude of themagnetic field produced by this wire at the ground?Problem 20-30Determine the magnitude and direction of the forcebetween two parallel wires 35 m long and 6.0 cm apart,each carrying 25 A in the same direction.II()µ I 7B o 4 π x10 T m/A (95 A )2 πr2π (8.5 m )µ I IF o 1 2L2π drFIdL(4π x10 7 T m/A ) (25 A )2 π (6.0 x10 2 m )2F B 2.2 x10 6 TMagnetism 20(35 m ) 7.3 x10 2 NMagnetism 204
2/26/2014Solenoids and ElectromagnetsSummaryMagnets have north and south polesLike poles repel, unlike attractUnit of magnetic field: teslaA solenoid is a long coil of wire. If it is tightly wrapped, themagnetic field in its interior is almost uniform:µ INB oLIElectric currents produce magnetic fieldsA magnetic field exerts aforce on an electric current:INBF ILB sin θA magnetic field exerts a forceon a moving chargeF qvB sin θLMagnetism 20Solenoids and ElectromagnetsSummaryProblem 20-48A thin 12-cm-long solenoid has a total of 420 turns of wireand carries a current of 2.0 A. Calculate the field insidenear the center.µ INB oL Magnetism 20Magnitude of the field of a long,straight current-carrying wireµ IB o2π rParallel currents attract;anti-parallel currents repel(4π x10 7 T m/A ) (2.0 A ) (420 )Magnetic field inside a solenoid(0.12 m )B 8.8 x10 3 TForce between to longstraight currents.Magnetism 20µ INB oLµ I IF o 1 2L2π dMagnetism 20Solenoids and ElectromagnetsProblem 20-49A 30.0-cm-long solenoid 1.25 cm in diameter is to producea field of 0.385 T at its center. How much current shouldthe solenoid carry if it has 975 turns of the wire?µ INB oLI I BLµo N(0.385 T )(0.300 m )(4π x10 7 T m/A ) (975 )B 94.3 AMagnetism 205
Electric Currents Produce Magnetic Fields Force on an Electric Current in a Magnetic Field Force on Electric Charge Moving in a Magnetic Field Magnetic Field Due to a Long Straight Wire Force between Two Parallel Wires Solenoids and Electromagnets Magnetism 20 Magnets have two ends – poles – called north and south.
Introduction of Chemical Reaction Engineering Introduction about Chemical Engineering 0:31:15 0:31:09. Lecture 14 Lecture 15 Lecture 16 Lecture 17 Lecture 18 Lecture 19 Lecture 20 Lecture 21 Lecture 22 Lecture 23 Lecture 24 Lecture 25 Lecture 26 Lecture 27 Lecture 28 Lecture
Magnetism (Section 5.12) The subjects of magnetism and electricity developed almost independently of each other until 1820, when a Danish physicist named Hans Christian Oersted discovered in a classroom demonstration that an electric current affects a magnetic compass. He saw that magnetism was related to electricity.
Lecture 1: A Beginner's Guide Lecture 2: Introduction to Programming Lecture 3: Introduction to C, structure of C programming Lecture 4: Elements of C Lecture 5: Variables, Statements, Expressions Lecture 6: Input-Output in C Lecture 7: Formatted Input-Output Lecture 8: Operators Lecture 9: Operators continued
Lecture 1: Introduction and Orientation. Lecture 2: Overview of Electronic Materials . Lecture 3: Free electron Fermi gas . Lecture 4: Energy bands . Lecture 5: Carrier Concentration in Semiconductors . Lecture 6: Shallow dopants and Deep -level traps . Lecture 7: Silicon Materials . Lecture 8: Oxidation. Lecture
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Partial Di erential Equations MSO-203-B T. Muthukumar tmk@iitk.ac.in November 14, 2019 T. Muthukumar tmk@iitk.ac.in Partial Di erential EquationsMSO-203-B November 14, 2019 1/193 1 First Week Lecture One Lecture Two Lecture Three Lecture Four 2 Second Week Lecture Five Lecture Six 3 Third Week Lecture Seven Lecture Eight 4 Fourth Week Lecture .
Students will be able to explain how electricity and magnetism work together in electric motors and generators. Anticipatory Set Students have learned about electricity, electric circuits, voltage, and current. They are familiar with how to connect circuit elements. Electricity and magnetism are closely related.
empirical psychology (in the 1770s in particular) and that of psychiatry (which was established firmly as a discipline in the German-speaking territories by 1820), animal magnetism changed from an experimental but somewhat accepted medical practice to a source of esoteric fascination. However, by continuing to focus on animal magnetism into the .
