Presentation on theme: "The Movement of Charged Particles in a Magnetic Field"— Presentation transcript:
1 The Movement of Charged Particles in a Magnetic Field ByEmily NashAndHarrison Gray
2 Preview Magnetic fields and how they are created Magnetic field of the earthSolar wind and how the earth’s magnetic field affects itTaking a look at the force that magnetic fields exert upon electrons by using a cathode ray tube, magnets, and some simple math.
3 Magnetic Fields N S Magnetic Fields are created by moving charged particles, and only affect movingcharged particles.Forces between two electric currents is what causes a magnetic force. Two parallel currents flowing in the same direction attract each other, while two parallel currents flowing in opposite directions repel each other.NWhen there exists a steadystream of electrons, a negatively charged particle, an electriccurrent forms, which producesa magnetic field.This force leads to the idea of the north and south poles of a magnetic field.S
4 Creating a Magnetic Field It is possible to create a magnetic field by producing an electric current, or vice versa.When current passes through a coil of wire, itgenerates a magnetic field along the access of the coil.This is called electromagnetismcurrent
5 Earth's Magnetic Field S N The Earth itself is a magnet, with a magnetic northpole and south pole.The origin of the Earth’s magnetic field is said to be a result of the dynamo effect, electric currents produced by the rotation of the iron-nickel core.SNThe Earth’s magnetic field continually traps moving charged particles coming from the sun, called solar wind.High concentrations of these particles within the field are called the Van Allen Radiation belts.
6 Solar Wind Magnetotail Bow Shock Magnetosheath Solar Wind consists of gases comprised of protons, electrons, and ions which hurl towards the earth from the sun at velocities of 450 km/sec or higher.Bow ShockThe path of these particles change almost directly as they hit the earth’s magnetosphere at the region called the bow shock.MagnetosheathThe impact of the solar wind causesThe field lines facing the sun to compress,While the field lines on the other side stream back to form aMagnetotail.Because the charged particles of the rays are deflected around the magnetosheath,the earth is protected from most of the deadly radiation.
7 contribute to the Van Allen radiation belts. Solar Wind CntdSome solar wind particles, however, do escape the earth’s magnetosphere andcontribute to the Van Allen radiation belts.When these particles do enter the magnetic field, they go through three motions:Spiral- the particle takes a spiraling motion around a magnetic field line.Bounce- the particles eventually bounce towards the opposite pole, where they spiral again.Drift- as the particle continually spirals and bounces, it drift around the magnetic field and is trapped in the magnetosphere.In order to better understand the motion of particles through a magnetic field,we have conducted an experiment involving creating an electron beam and running it through magnets as a parallel to solar wind entering the earth’s magnetic field.
8 √Cathode Ray Tube Cntd.Since change in energy is the voltage times the chargethen ½mv²=qVTherefore v= √(2qV/m)The potential energyof electrons is convertedto kinetic energyElectrons are attracted to positively chargedplate. They accelerate towards it and smallpercentage escape the plate through smallhole, creating electron beam.120 VoltsPlate is heated andelectrons boil off.Velocity= 0Potential Energy= ½ mv^26.3 Volts
10 Calculating the Velocity of the Electrons We now know that v= √(2qV/m), so we can now easily find thevelocity of our beam of electrons.q(charge) of an electron= -1.6•10^-19V(volts)=120m(mass) of an electron=9.11•10^-31 kgTherefore:v=√(2)(-1.6•10^-19)(120)/(9.11•10^-31)v=√4.215•10^13v=649•10^6 m/s
11 Bending Electron Beams In order to predictthe angle at whichthe electrons aredeflected, we mustfirst measurethe force that themagnetic field insertsupon the beamTo do this, we use the equation:F=qvBLike Solar Wind,the electrons in theCRT beam are deflectedwhen entering amagnetic field,therefore the electronbeam “bends.”Magnetic fieldThe force is alwaysPerpendicular to the magnetic fieldAnd the velocity of the electronsElectrons
12 Calculating the Strength of the Magnetic Field In order to find the force of the magnetic field, we must first calculate its strenghth.Since F=qvB and, according to Newton’s second law, F=m•v²/r, we can deduce thatqvB=m•v²/rOrB=mv/qrmass= 9.11•10^-31 kgvelocity= 6.492•10^6 m/sCharge= 1.6•10^-19 CAnd we measured the distance of the electron beam from the magnetsto be .075 metersTherefore B= (9.11•10^-31)(6.492•10^6)/(1.6•10^-19)(.075)B=2.772•10^-6 tesla
13 Calculating the Force of the Magnetic Field Now that we know the strength of the magnetic field at the electron beam, we canCalculate the force which the field exerts upon the electrons.F=qvBF=(649•10^6)/(1.6•10^-19)(2.772•10^-6F=2.879•10^-18 N
14 Conclusion Basics of Magnetic fields and electromagnetism The earth’s magnetic field and how it shields the earth from solar windThe movement of charged particles such as solar wind as they enter a magnetic fieldHow to find the force that magnetic field exerts upon charged particles and the strength of the field itself.How to predict the path of a charged particle through a magnetic field