Exam 24: Magnetic Fields and Forces

A flat circular wire loop of area 0.25 m² carries a current of 5.0 A. This coil lies on a horizontal table with the current flowing in the counterclockwise direction when viewed from above. At this point, the earth's magnetic field is 1.2 × 10^-5 T directed 60° below the horizontal. What is the magnitude of the torque that the earth's magnetic field exerts on this loop?

A proton, moving east, enters a magnetic field. Because of this magnetic field the proton curves downward. We may conclude that the magnetic field must have a component

A flat coil containing 25 identical loops carries 6.4 A of current. When it is placed in a uniform magnetic field of 0.22 T that is oriented parallel to the plane of the coil, the magnetic torque on it is 3.7 N ? m. (a)What is the magnetic moment of the coil? (b)What is the area of each loop?

In the figure, the rectangular loop is pivoted about one side (of length 0.060 m), that coincides with the y-axis. The end (length 0.020 m)of the loop that lies in the xz-plane makes an angle of 37° with the x-axis as shown. The loop carries a current of I = 69 A in the direction shown. (In the side of the loop that is along the y-axis the current is in the +y direction.)If there is a uniform magnetic field of magnitude 9.7 T in the -x direction, find the magnitude of the torque that this magnetic field exerts on the loop.

A flat circular coil of wire having 200 turns and diameter 6.0 cm carries a current of 7.0 A. It is placed in a magnetic field of $0.60 \mathrm {~T}$ with the plane of the coil making an angle of 30° with the magnetic field. What is the magnitude of the magnetic torque on the coil?

The magnetic field at point P due to a 2.0-A current flowing in a long, straight, thin wire is 8.0 μT. How far is point P from the wire? (μ₀ = 4π × 10^-7 T ∙ m/A)

When a ferromagnetic material is placed in an external magnetic field, the net magnetic field of its magnetic domains becomes

Which of the following are units for the magnetic moment? (There could be more than one correct choice.)

A charged particle moving along the +x-axis enters a uniform magnetic field pointing along the +z-axis. A uniform electric field is also present. Due to the combined effect of both fields, the particle does not change its velocity. What is the direction of the electric field?

A straight bar magnet is initially 4 cm long, with the north pole on the right and the south pole on the left. If you cut the magnet in half, the right half will

A flat circular loop of wire is in a uniform magnetic field of 0.30 T. The diameter of the loop is 1.0 m, and a 2.0-A current flows in it. What is the magnitude of the magnetic torque on the loop when the plane of the loop is parallel to the magnetic field?

When the switch is closed in the circuit shown in the figure, the wire between the poles of the horseshoe magnet deflects upward. From this you can conclude that the left end of the magnet is

An ideal solenoid having a coil density of 5000 turns per meter is 10 cm long and carries a current of 4.0 A. What is the strength of the magnetic field at its center?

Consider an ideal solenoid of length L, N windings, and radius b (L is much longer than b). A current I is flowing through the wire windings. If the radius of the solenoid is doubled to 2b, but all the other quantities remain the same, the magnetic field inside the solenoid will

A proton, starting from rest, accelerates through a potential difference of 1.0 kV and then moves into a magnetic field of 0.040 T at a right angle to the field. What is the radius of the proton's resulting orbit? (e = 1.60 × 10^-19 C, m_proton = 1.67 × 10^-27 kg)

When you double the number of windings in an ideal solenoid while keeping all other parameters (radius, length and current)fixed, the magnetic field at the center of the solenoid will

The magnetic field at a distance of 2 cm from a long straight current-carrying wire is 4 μT. What is the magnetic field at a distance of 4 cm from this wire?

A long, straight wire carrying a current is placed along the y-axis. If the direction of the current is in the +y direction, what is the direction of the magnetic field due to this wire as you view it in such a way that the current is coming directly toward you?

Three very long, straight, parallel wires each carry currents of 4.0 A, directed out of the page as shown in the figure. These wires pass through the vertices of a right isosceles triangle as shown. Assume that all the quantities shown in the figure are accurate to two significant figures. What is the magnitude of the magnetic field at point P at the midpoint of the hypotenuse of the triangle? (μ₀ = 4π × 10^-7 T ∙ m/A)

An electron is moving to the right, as shown in the figure. Suddenly it encounters uniform magnetic field pointing out of the page. Which one of the three paths shown will it follow in the field?