Exam 31: Faradays Law

A small airplane with a wing span of 12 m flies horizontally and due north at a speed of 60 m/s in a region where the magnetic field of the earth is 60 μT directed 60° below the horizontal. What is the magnitude of the induced emf between the ends of the wing?

The coil shown in the figure has 2 turns, a cross-sectional area of 0.20 m², and a field (parallel to the axis of the coil) with a magnitude given by B = (4.0 + 3.0t²) T, where t is in s. What is the potential difference, V_A − V_C, at t = 3.0 s?

In a region of space where the magnetic field of the earth has a magnitude of 80 μT and is directed 30° below the horizontal, a 50-cm length of wire oriented horizontally along an east-west direction is moved horizontally to the south with a speed of 20 m/s. What is the magnitude of the induced potential difference between the ends of this wire?

As shown below, a square loop of wire of side a moves through a uniform magnetic field of magnitude B perpendicular to the page at constant velocity directed to the right. Which statement regarding the electric field induced in the wires is correct for the wires at the left and right sides of the loop?

A current may be induced in a coil by

The difference between a DC and an AC generator is that

The magnetic flux through a loop perpendicular to a uniform magnetic field will change

A conducting rectangular loop of mass M, resistance R, and dimensions a × b is allowed to fall from rest through a uniform magnetic field which is perpendicular to the plane of the loop. The loop accelerates until it reaches a terminal speed (before the upper end enters the magnetic field). If a = 2.0 m, B = 6.0 T, R = 40 Ω, and M = 0.60 kg, what is the terminal speed?

A metal blade spins at a constant rate of 5.0 revolutions per second about a pivot through one end of the blade. This rotation occurs in a region where the component of the earth's magnetic field perpendicular to the blade is 30 μT. If the blade is 60 cm in length, what is the magnitude of the potential difference between its ends?

A circular loop (area = 0.20 m²) turns in a uniform magnetic field with B = 0.13 T. At an instant when the angle between the magnetic field and the normal to the plane of the loop is (π) rads and is decreasing at the rate of 0.50 rad/s, what is the magnitude of the emf induced in the loop?

A coil is wrapped with 300 turns of wire on the perimeter of a square frame (side length = 20 cm). Each turn has the same area as the frame, and the total resistance of the coil is 1.5 Ω. A uniform magnetic field perpendicular to the plane of the coil changes in magnitude at a constant rate from 0.50 T to 0.90 T in 2.0 s. What is the magnitude of the induced emf in the coil while the field is changing?

A conducting bar moves as shown near a long wire carrying a constant 80-A current. If a = 1.0 mm, b = 20 mm, and v = 5.0 m/s, what is the potential difference, V_a − V_b?

An induced emf is produced in

A flat coil of wire consisting of 20 turns, each with an area of 50 cm², is positioned perpendicularly to a uniform magnetic field that increases its magnitude at a constant rate from 2.0 T to 6.0 T in 2.0 s. If the coil has a total resistance of 0.40 Ω, what is the magnitude of the induced current?

A conducting bar of length L rotates in a counterclockwise direction with a constant angular speed of +2.0 rad/s about a pivot P at one end, as shown. A uniform magnetic field (magnitude = 0.20 T) is directed into the paper. If L = 0.40 m, what is the potential difference, V_A − V_B?

A long solenoid (n = 1 500 turns/m) has a cross-sectional area of 0.40 m² and a current given by I = (4.0 + 3.0t²) A, where t is in seconds. A flat circular coil (N = 300 turns) with a cross-sectional area of 0.15 m² is inside and coaxial with the solenoid. What is the magnitude of the emf induced in the coil at t = 2.0 s?

A rectangular wire loop (length = 60 cm, width = 40 cm) lies completely within a perpendicular and uniform magnetic field of magnitude of 0.5 T. If the length of the loop starts increasing at a rate of 20 mm/s at time t = 0, while the width is decreasing at the same rate, what is the magnitude of the induced emf at time t = 4.0 s?

A metal blade (length = 80 cm) spins at a constant rate of 10 radians/s about a pivot at one end. A uniform magnetic field of 2.0 mT is directed at an angle of 30° with the plane of the rotation. What is the magnitude of the potential difference between the two ends of the blade?

Starting outside the region with the magnetic field, a single square coil of wire moves across the region with a uniform magnetic field perpendicular to the page. The loop moves at constant velocity . As seen from above, a counterclockwise emf is regarded as positive. Roger claims that the graph shown below represents the induced emf. Martin says he's wrong. In which direction did the loop move over the plane of the page, or is Martin correct?

A long straight wire is parallel to one edge and is in the plane of a single-turn rectangular loop as shown. If the loop is moving in the plane shown so that the distance x changes at a constant rate of 20 cm/s, what is the magnitude of the emf induced in the loop at the instant x = 5.0 cm? Let I = 50 A, a = 50 cm, b = 6.0 cm.