Exam 28: Magnetic Fields

A coil of 1000 turns of wire has a radius of 12 cm and carries a counterclockwise current of 15A.If it is lying flat on the ground, and the Earth's magnetic field points due north, has a magnitude of 5.8 x 10^-5 T, and makes a downward angle of 25° with the vertical, what is the torque on the loop?

A square loop of wire lies in the plane of the page and carries a current I as shown.There is a uniform magnetic field directed towards the top of the page, as indicated.The loop will tend to rotate:

For a loop of current-carrying wire in a uniform magnetic field the potential energy is a minimum if the magnetic dipole moment of the loop is:

The Hall effect can be used to calculate the charge-carrier number density in a conductor.If a conductor carrying a current of 2.0 A is 0.5 mm thick, and the Hall effect voltage is 4.5 µV when it is in a uniform magnetic field of 1.2 T, what is the density of charge carriers in the conductor?

A conducting strip of width 1.5 mm is in a magnetic field.As a result, there is a potential difference of 4.3 mV across the width of the strip.What is the magnitude of the electric field in the strip?

An electron travels due north through a vacuum in a region of uniform magnetic field that is also directed due north.It will:

A proton (charge e), traveling perpendicular to a magnetic field, experiences the same force as an alpha particle (charge 2e)which is also traveling perpendicular to the same field.The ratio of their speeds, v_proton/v_alpha is:

An electron enters a region of uniform perpendicular and fields.It is observed that the velocity of the electron is unaffected.A possible explanation is:

A strip 1.2 mm wide is moving at a speed of 25 cm/s through a uniform magnetic field of 5.6 T.What is the maximum Hall voltage across the strip?

Units of a magnetic field might be:

A uniform magnetic field is in the positive z direction.A positively charged particle is moving in the positive x direction through the field.The net force on the particle can be made zero by applying an electric field in what direction?

An ion with a charge of +3.2 *10^?19 C is in region where a uniform electric field of 5 F*10^4.V/m is perpendicular to a uniform magnetic field of 0.8 T.If its acceleration is zero then its speed must be:

At one instant an electron is moving in the positive x direction along the x axis in a region where there is a uniform magnetic field in the positive z direction.When viewed from a point on the positive z axis, it subsequent motion is: