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Physics II exam 2, Chapters 30-35

Terms in this set (108)

A coil is wrapped with 300 turns of wire on the perimeter of a circular frame (radius = 8.0 cm). Each turn has the same area, equal to that of the frame. A uniform magnetic field is turned on perpendicular to the plane of the coil. This field changes at a constant rate from 20 to 80 mT in a time of 20 ms. What is the magnitude of the induced emf in the coil at the instant the magnetic field has a magnitude of 50 mT?
a. 24 V
b. 18 V
c. 15 V
d. 10 V
e. 30 V
b-18 V
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. 0.70 A
b. 0.60 A
c. 0.50 A
d. 0.80 A
e. 0.20 A
c-0.50 A
A 400-turn circular coil (radius = 1.0 cm) is oriented with its plane perpendicular to a uniform magnetic field which has a magnitude that varies sinusoidally with a frequency of 90 Hz. If the maximum value of the induced emf in the coil is observed to be 4.2 V, what is the maximum value of the magnitude of the varying magnetic field?
a. 59 mT
b. 62 mT
c. 65 mT
d. 68 mT
e. 31 mT
a)59 mT
A square loop (length along one side = 20 cm) rotates in a constant magnetic field which has a magnitude of 2.0 T. At an instant when the angle between the field and the normal to the plane of the loop is equal to 20° and increasing at the rate of 10°/s, what is the magnitude of the induced emf in the loop?
a. 13 mV
b. 0.27 V
c. 4.8 mV
d. 14 mV
e. 2.2 mV
c)4.8 mV
A loop of wire (resistance = 2.0 mΩ) is positioned as shown with respect to a long wire which carries a current. If d = 1.0 cm, D = 6.0 cm, and L = 1.5 m, what current is induced in the loop at an instant when the current in the wire is increasing at a rate of 100 A/s?
a. 34 mA
b. 30 mA
c. 27 mA
d. 38 mA
e. 0.50 mA
c)27 mA
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. 2.4 V
b. 1.6 V
c. 3.2 V
d. 4.0 V
e. 8.4 V
a)2.4 V
A planar loop consisting of four turns of wire, each of which encloses 200 cm2 , is oriented perpendicularly to a magnetic field that increases uniformly in magnitude from 10 mT to 25 mT in a time of 5.0 ms. What is the resulting induced current in the coil if the resistance of the coil is 5.0 Ω?
a. 60 mA
b. 12 mA
c. 0.24 mA
d. 48 mA
e. 6.0 mA
d)48 mA
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 changing width so that the distance x changes at a constant rate of 4.0 cm/s, what is the magnitude of the emf induced in the loop at an instant when x = 6.0 cm? Let a = 2.0 cm, b = 1.2 m, and I = 30 A.

a. 5.3 μV
b. 2.4 μV
c. 4.8 μV
d. 2.6 μV
e. 1.3 μV
c)4.8 μV
A circular loop (area = 0.20 m 2 ) 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. zero
b. 13 mV
c. 26 mV
d. 20 mV
e. 18 mV
a)zero
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. 0.24 mV
b. 0.20 mV
c. 0.17 mV
d. 0.27 mV
e. 0.34 mV
c)0.17 mV
A 20-cm length of wire is held along an east-west direction and moved horizontally to the north with a speed of 3.0 m/s in a region where the magnetic field of the earth is 60 μT directed 30° below the horizontal. What is the magnitude of the potential difference between the ends of the wire?
a. 36 μV
b. 18 μV
c. 31 μV
d. 24 μV
e. 21 μV
b)18 μV
In the arrangement shown, a conducting bar of negligible resistance slides along horizontal, parallel, frictionless conducting rails connected as shown to a 2.0-Ω resistor. A uniform 1.5-T magnetic field is perpendicular to the plane of the paper. If L = 60 cm, at what rate is thermal energy being generated in the resistor at the instant the speed of the bar is equal to 4.2 m/s?
a. 8.6 W
b. 7.8 W
c. 7.1 W
d. 9.3 W
e. 1.8 W
c)7.1 W
A rod (length = 10 cm) moves on two horizontal frictionless conducting rails, as shown. The magnetic field in the region is directed perpendicularly to the plane of the rails and is uniform and constant. If a constant force of 0.60 N moves the bar at a constant velocity of 2.0 m/s, what is the current through the 12-Ω load resistor?
a. 0.32 A
b. 0.34 A
c. 0.37 A
d. 0.39 A
e. 0.43 A
a)0.32 A
A conducting rod (length = 2.0 m) spins at a constant rate of 2.0 revolutions per second about an axis that is perpendicular to the rod and through its center. A uniform magnetic field (magnitude = 8.0 mT) is directed perpendicularly to the plane of rotation. What is the magnitude of the potential difference between the center of the rod and either of its ends?
a. 16 mV
b. 50 mV
c. 8.0 mV
d. 0.10 mV
e. 100 mV
b)50 mV
A small airplane with a wingspan 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?
a. 50 mV
b. 31 mV
c. 37 mV
d. 44 mV
e. 22 mV
c)37 mV
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