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27 Nov 2019

Induced emf measurements can be used to measure the speed of a conducting fluid such as sea water. If a 20 cm inner diameter nonconducting pipe has sea water flowing through it at a flow rate of 10 gal/min and a uniform magnetic field of 0.05 T is applied transversely across the pipe, find the induced emf across a diameter.

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Patrina Schowalter
Patrina SchowalterLv2
16 May 2019

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Related textbook solutions

Physics: Principles with Applications
7th Edition, 2013
Giancoli
ISBN: 9780321625922

Related questions

1a) Faraday discovered that a current is induced in a coil

A) only when the N pole of a magnet is inside the coil
B) only when the S pole of a magnet is inside the coil
C) only when there is a magnetic field inside the coil
D) only when the magnetic field inside the coil is changing

1b). A conductor moves through a uniform magnetic field at speed v and has a motional emf V created across it. If the conductor were to move twice as fast through the magnetic field, the motional emf would be:

A) V
B) 2V
C) 4V
D) V/2
E) V/4

1c) In the conducting rail discussed in section 25.2 (where the rail is moving at constant speed), what can you say about the power input due to the person pulling on the rail and the power dissipated in the resistance?

A) Power input from pull = power dissipated in R
B) Power input from pull > power dissipated in R
C) Power input from pull < power dissipated in R

1d) The electric generator as shown in the reading generates electricity by:

A) rotating a loop inside a magnetic field
B) moving a magnet in and out of a loop
C) sliding a loop over a magnet
D) running current through a loop in a magnetic field

1e) The magnetic flux through a loop:

A) is proportional to the number of magnetic field lines going through it
B) depends just on the B field going through the loop
C) is maximized when the B field lines in the plane of the loop
D) is zero when the B field is perpendicular to the plane of the loop
E) doesn't depend on the direction of the B field

1f) According to Lenz's Law, the induced B field (due to the induced current) will:

A) be in the opposite direction of the existing B field
B) be in the same direction as the existing B field
C) be in the same direction as the change in the existing B field
D) be in the opposite direction of the change in the existing B field

1g) A stationary coil experiences a doubling of its magnetic field (no change in direction of the field) in a time T and has a given induced EMF. If the same change were to have happened in half the time (T/2), the induced EMF would have been:

A) half as large
B) the same
C) twice as large
D) one-fourth as large
E) four times as large

1h) Eddy currents:

A) make it hard to pull a nonmagnetic material through a magnetic field
B) make it hard to pull a magnetic material through a magnetic field
C) speed up a magnetic material moving through a magnetic field
D) speed up a nonmagnetic material moving through a magnetic field

 

 

1)As shown in the figure, a uniform conducting rod of length 0.40 m and mass 0.075 kg is in rotational equilibrium about the hinge at point O. A uniform magnetic field of 0.23 T is directed out of the plane of the page, perpendicular to the rod. Due to a battery and wires not shown, there is a current of 4.0 A in the rod directed toward point O. Determine the angle θ.

Image for As shown in the figure, a uniform conducting rod of length 0.36 m and mass 0.075 kg is in rotational equilibri

2)As shown in the figure, a conducting rod with a length of 0.79 m is placed on a horizontal frictionless surface and attached to a power supply by two springs, each with a spring constant of 81 N/m. The springs are initially at their equilibrium length and are in a region where there is a uniform magnetic field of 0.17 T that is perpendicular to the frictionless surface when the power supply supplies a current that causes the wire to move in such a direction that the two springs are stretched.

A top view of a table shows an arrow field labeled vector B pointing down into the table. On the table a rod lies from the top of the image to the bottom of the image, with a spring attached to the right side of the rod near the top and bottom. The springs are connected to wires that are attached to a power supply.
(a) Determine the stretch of each spring, if the current through the rod is 11 A.
 
3)A conducting rod of length L = 30.5 cm slides over two horizontal metal bars with a constant speed v to the left through a distance Δx in a time Δt. The entire set up is in a region of uniform magnetic field of magnitude 1.30 T that is directed perpendicular to the rods and out ofthe page.
(a) If the induced emf has a magnitude of 1.00 V, what is the speed with which the rod moves?
 
4)An MRI technician moves his hand from a region of very low magnetic field strength into an MRI scanner's 2.00-T field with his fingers pointing in the direction of the field.
(a) Find the average emf induced in his wedding ring, given its diameter is 2.34 cm and assuming it takes 0.222 s to move it into the field.


(b) If the resistance of the ring is 1.00 mΩ, how much heat will be transferred to the ring during this time?

 

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The conducting rod ab shown in the figure makes contact with metal rails ca and db. The apparatus is in a uniform magnetic field of 0.800 T, perpendicular to the plane of the figure.
a) Find the magnitude of the emf induced in the rod when it is moving toward the right with a speed of 7.50 m/s.
b) In what direction does the current flow in the rod?
c) If the resistance of the circuit abdc is 1.50 Ω (assumed to be constant), find the force (magnitude and direction) required to keep the rod moving to the right with a constant speed of 7.50 m/s. You can ignore friction.
d) Compare the rate at which mechanical work is done by the force (Fv) with the rate at which thermal energy is developed in the circuit (I2R).

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