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28 Cards in this Set
- Front
- Back
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What is the relationship between an electric field and a magnetic field?
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A changing magnetic field will produce an electric field and a changing electric field will produce a magnetic field.
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What is the source of any magnetic field?
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Magnetic fields are always produced by moving charge. This can be an electron moving through a wire or any charged particle moving through space. This will always produce a magnetic field.
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SI unit for magnetism
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Tesla. 1 Tesla = 1 N * s/m * C
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What unit will be used for smaller magnetic fields?
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Gauss. 1T = 10^4 gauss
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Designation of the arrow of a magnetic field vector that is coming out of the page.
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A dot will represent a magnetic field line that is coming out of the page.
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Designation of the arrow of a magnetic field vector that is going into the page.
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An X will represent a magnetic field line that going into the page
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Diamagnetic
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These materials have no unpaired electrons and will have no magnetic characters
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Paramagnetic materials
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Paramagnetic materials have unpaired electrons and will become weakly magnetized in a magnetic field. The atoms of the material will shift to one pole of the magnet or the other upon exposure to a magnetic field.
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Ferromagnetic Materials
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These materials have unpaired electrons and will become very magnetized upon exposure to a magnetic field or high temperatures. At these points, there will be a high degree of alignment of the magnetic fields of the atoms.
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Curie Temperature
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Above this temperature, the material is paramagnetic. However, below this temperature, the material becomes highly magnetized.
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What is the shape of magnetic field lines.
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The shape of magnetic field lines is circular
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Current moving through a wire
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An electric current moving through a wire will produce a magnetic field. That magnetic field will be the vector sum of all the magnetic fields of the or the charges moving through the wire
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Electric Current
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The units of current are Amperes (i). 1 A = 1 coulomb/sec. (i) can be calculated i = Δq/Δt
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Direction of current
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The direction of the current will be in the opposite direction of where the electrons would flow. The convention for current is the direction in which positive charge would flow from a higher potential to a lower potential.
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Straight Current Carrying Wire
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The magnetic field (B) is directly related to the distance from the wire (r). As you move further from the wire, the strength of the magnetic field will become weaker and weaker.
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Right Hand Rule for Straight Current Carrying wire
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-- This is the RIGHT hand rule to make sure to use that hand
-- Orient your right hand thumb in the direction of the current. Then wrap your fingers around the wire. The tips of your fingers will tell you the direction of the magnetic field. --Note on practice question: you were given a wire with lines coming from the left side and the right side and you were asked to find the direction of the magnetic field as those point. This is very simple. Just take your open right hand and orient your thumb in the direction of the current. At this point your hand should be flat and open. Then, start curling your fingers around the wire and stop at the point your finger tips hit the point that you are working on. Your finger tips will either be pointing into the page or out of the page. |
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Difference between equations for Straight Current Carrying Wire and Circular Current Carrying Wire.
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The difference is that the equation for the straight wire will give you the strength of the magnetic field at a distance r from the wire while the equation for the circular current carrying wire will only give you the magnetic field at the center of loop with a radius r
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Right Hand Rule and Determining magnetic field of circular loop
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The magnetic field within the loop will run in the opposite direction than it would outside the loop. The right hand rule will be the same. Right thumb will be in the direction in the current and finger tips will point in the direction of the magnetic field
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If the current in flowing in a certain direction, where will the electron flow be?
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Electrons flow in the opposite direction of the current.
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How do charges experience force?
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A charge will only experience a force that is generated by an external magnetic field or moving electric charge. Whenever there is a force on a charged particle, it means that there is another magnetic field in the area creating that force. This however, is only a convention to help us understand how magnetic field forces work.
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Force on a charged particle moving in a magnetic field.
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Force on a charge particle moving in a magnetic field is given by F = q v B sin(x). sin (x) is the sin of the angle between the direction the particle is moving in and the direction of the magnetic field. q = the value of the charge of moving through the magnetic field. v = the velocity with which the charge is moving. B = the magnitude of the magnetic field
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Right Hand Rule for Force Due to Magnetic Field
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-- Determine the value of qv. If it is positive, then point your right hand thumb in the direction the particle is traveling in. If it is negative, then point your thumb in opposite direction the particle is traveling in.
--The direction in which the particle is moving will be perpendicular to the direction to the magnetic field. This means that your thumb and fingers have to make a 90 degree angle. --Orient your thumb in the direction of qv is positive and opposite qv if negative. After this, extend your fingers. The tips of your fingers will point in the direction of the magnetic field. -- Look at your palm, the direction of the force will be going out of your palm |
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What will happen to a charged particle that moves into a magnetic field?
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The charges particle will start moving in a circular path that is perpendicular to the magnetic field. This make total sense since magnetic fields are perpendicular to electric fields
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Equation for charged particle moving into a magnetic field
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F = qvB = mv^2/r
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What is the relationship between the centripetal force and the instantaneous velocity vector?
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They are perpendicular to each other. The centripetal force pulls the object to the center of the circle while the instantaneous velocity vector acts tangent to the circle which is perpendicular to the centripetal force.
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How will changing the magnetic field acting on a particle moving in circular motion affect the velocity and path of the particle?
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The magnetic field will have no effect on the velocity. The reason for this is that the centripetal force acting on the particle (circular motion come into play here) does no work on the particle. The equation for work is fdcos(x). In case of circular motion, there is 90 degrees between the velocity of the particle and the centripetal force which means that cos(90) will be function for work and that is obviously 0. This means that the centripetal force does no work. The only thing that will be affected is the path take by the particle.
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Force on a current carrying wire place in a magnetic field
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The force on the wire when place in a magnetic field is given by F = iLBsin(x). L is the length of the wire
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Right Hand Rule for Force acting on current carrying wire.
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--This is the same rule we use for force that we saw before but the only difference is that your thumb will always point in the direction of the current.
--Your thumb will point in the direction of the current. -- The thumb and fingers need to be at 90 degree angles. Extend your finger and this will give you the direction of the magnetic field --The force will be coming out of your palm |
