Exam 27: Magnetism

The Hall affect is used to measure the carrier density of a thin sheet of electrons.When a current of 80.0 $\mu$ A flows through the length of the electron sheet,which is 1.2-mm long,0.27-mm wide and 12-nm thick,a magnetic field of 0.75 T perpendicular to the sheet produces a potential difference across the width of the sheet.If the carrier density in the electron sheet is 6.74 * 10²⁵ m^-3,what potential difference is produced across the width of the sheet?

What is the magnitude of the force on an electron moving with a velocity of 6.33 * 10⁶ m/s at right angles to a 2.53 *10^-2 T magnetic field?

A proton with an initial velocity of (1.0x + 2.0y + 3.0z)* 10⁵ m/s enters a magnetic field of 0.50z T.Find the magnitude of the force on the proton.The mass of the proton is 1.67 *10^-27 kg.Where x,y and z are unit vectors in the x,y and z directions,respectively.

A proton with an initial velocity of (1.0x + 2.0y + 3.0z)* 10⁵ m/s enters a magnetic field of 0.50z T.Find the magnitude of the acceleration of the proton.The mass of the proton is 1.67 * 10^-27 kg.Where x,y and z are unit vectors in the x,y and z directions,respectively.

Thirty turns of wire are tightly wrapped into a coil around a round pencil that has a diameter of 6.0 mm.The pencil is then placed into a uniform B = 8.0 T magnetic field as shown in the figure.If a 4.0-A current is present in the coil of wire,what is the magnitude of the torque on the pencil?

A copper wire of radius 0.5 mm at the Earth's equator carries a current.Assuming that the magnetic field of the earth of 0.5 G at the equator is parallel to the surface of the Earth and that the current flows to the east,what is the current necessary in the wire to allow it to levitate?

A straight wire of length 3.5 m carries a current of 42 A and it is placed on a horizontal table in a horizontal uniform magnetic field of 0.14 T.If the wire makes an angle of 44 ^$\circ$ with the magnetic field lines,what is the magnitude of the magnetic force on the wire?

A straight wire of length 3.5 m carries a current of 42 A and it is placed on a horizontal table in a horizontal uniform magnetic field of 0.14 T.If the magnitude of the magnetic force on the wire is 9.0 N,what is the angle the between the wire and the magnetic field lines?

The figure shown depicts the cross section of a current carrying ring of wire having a radius of 4 cm.A 1-A current flows in the ring in the direction indicated in the drawing.The ring is free to rotate,clockwise or counterclockwise,about an axis normal to the page which passes through its center.The ring is connected to a spring with a spring constant of 100 N/m as shown.The spring is fixed to a wall at the other end.When the ring is in the vertical position,the spring is at its natural length.One may assume that the length of the spring is long enough such that any extension or compression follows Hooke's law.Determine the magnitude of the change in length of the spring when a magnetic field B = 2 T is applied along the vertical axis.

A copper wire at the Earth's equator carries a 2340 A current.Assuming that the magnetic field of the earth of 0.5 G at the equator is parallel to the surface of the Earth and that the current flows to the east,what is the largest radius of the wire that can be levitated by the magnetic field?

A positive charge enters a region of uniform magnetic field as shown in the figure.The initial direction of deflection of the charge is

A 0.3-m long wire carries 10 A of current as shown.If the magnetic force F on it is 3 N,what is the magnitude and direction of the field?

An electron that is accelerated from rest through a potential of 4.00 kV enters the velocity filter,consisting of a parallel plate capacitor and a magnetic field.The E-field between the parallel capacitor plates is 7.80 *10⁶ N/C.What magnetic field (in T)is required so that the electrons are not deflected? The mass of an electron is 9.11 * 10^-31 kg.(Ignore relativistic effects for high velocities.)

Carbon-12 and Carbon-14 atoms,(12 and 14 atomic mass units,respectively)each missing one electron,so that they carry +1e electric charge,pass through a velocity selector (therefore have the same speed)and then pass through a hole in a vertical lead plate into a region of uniform magnetic field,also oriented vertically.What is the ratio of the radii of curvature r₁₂/r₁₄ for these two atoms' paths?

A 0.320 kg,25-turn square coil has a side of 0.210 m,is hinged along a horizontal side and carries a 6.0-A current.When placed in a vertical magnetic field pointing down,the plane of the coil makes a 7.3 ^$\circ$ angle with the vertical when the coil is in equilibrium.Determine the magnitude of the magnetic field.Use g = 9.81 m/s².

A rectangular 30-turn coil of wire,with width of 12.0 cm along the y-axis and height of 25.0 cm along the z-axis,is placed in a uniform external magnetic field with an x-component of 0.0951 T and a y-component of 0.182 T.The coil is hinged along the y-axis and is located in the yz-plane.A current of 0.350 A flows through the wire.What is the magnitude of the torque that B exerts on the coil?

A magnetic field is oriented in a certain direction in the horizontal plane.A charged particle travels in a certain direction in the horizontal plane.Given just this information,there

A proton with an initial velocity of (1.0x + 2.0y + 3.0z)x 10⁵ m/s enters a magnetic field of 0.50z T.Find the radius of the resulting helix.The mass of the proton is 1.67 * 10²⁷ kg.Where x,y and z are unit vectors in the x,y and z directions,respectively.

An electron is accelerated from rest through a voltage of 600 V.The electron enters a uniform magnetic field of magnitude 5.7 * 10^-2 T and follows a circular path.Determine the radius of the circular path.

A 25-turn square coil with a mass of 0.320 kg and a side of 0.210 m is hinged along a horizontal side,carries a 6.00-A current and is placed in a vertical magnetic field pointing down and having a magnitude of 4.00 mT.Determine the angle that the plane of the coil makes with the vertical when the coil is in equilibrium.Use g = 9.81 m/s².