Concept explainers
You are part of a team working in a machine parts mechanic’s shop. An important customer has asked your company to provide springs with a very precise force constant k. To measure the spring constant, you fasten two of the springs between the ends of two very long wires of length L, separated by the unstretched length ℓ of the springs as shown in Figure P29.15. The specific attachment method that you use insulates the springs from the wires so that no current passes through the springs. You lay the apparatus flat on a table and then pass a current of magnitude I through the wires, in opposite directions. As a result the springs stretch by a distance d and come to equilibrium. You determine an expression for the spring constant in terms of L, I, ℓ, and d.
Figure P29.15
Trending nowThis is a popular solution!
Chapter 29 Solutions
PHYSICS:F/SCI.+ENGRS-W/WEBASSIGN
- (a) What is the average power output of a heart defibrillator that dissipates 400 J of energy in 10.0 ms? (b) Considering the high-power output, why doesn’t the defibrillator produce serious bums?arrow_forwardA rail gun uses electromagnetic forces to accelerate a projectile to very high velocities. The basic mechanism of acceleration is relatively simple and can be illustrated in the following example. A metal rod of mass 40.0 g and electrical resistance 0.300 Ω rests on parallel horizontal rails that have negligible electric resistance. The rails are a distance L = 9.00 cm apart. (Figure 1)The rails are also connected to a voltage source providing a voltage of V = 5.00 V .The rod is placed in a vertical magnetic field. The rod begins to slide when the field reaches the value B = 0.131 T . Assume that the rod has a slightly flattened bottom so that it slides instead of rolling. Use 9.80 m/s^2 for the magnitude of the acceleration due to gravity. A) Find μ_s, the coefficient of static friction between the rod and the rails. Give the answer numericallyarrow_forwardWhen operated on a household 110.0 V line, typical hair dryers draw about 1650 W of power. The current can be modeled as a long, straight wire in the handle. During use, the current is about 2.15 cm from the user's hand. What is the current in the hair dryer? A What is the resistance of the hair dryer? Ω What magnetic field does the hair dryer produce at the user's hand? The permeability of free space is ?0=4?×10−7 N/A2.arrow_forward
- Question: V Figure 1. A rectangular sample of semiconductor is in a magnetic field B, oriented approximately into the page, as shown. The sample is connected to an ammeter, voltmeter and a voltage source. The schematic shows a circuit involving a sample of semiconductor, whose cross-section is L by w. The sketch is not to scale and the electrodes attached to the sample are not shown. A uniform magnetic field B is applied in the direction indicated by the crosses (roughly, into the page). Each charge carrier has a charge q and the density of charge carriers, measured in ions per cubic metre, is n. Part 1) Use the definition of electric current to give an expression for the average speed of the charge carriers when the ammeter registers a current i. vd = Part 2) Give an expression for the magnitude of the magnetic force on a charge carrier. Your answer should be in terms of ¿, not v. F= Part 3) The magnetic force in part 2 produces a lateral displacement in the charge carriers, and the…arrow_forwardWhy is the following situation impossible? A politician is decrying wasteful uses of energy and decides to focus on energy used to operate plug-in electric clocks in the United States. While many people use their smartphone as an alarm clock, he estimates that there are still 270 million plug-in alarm clocks in continuous use. The clocks transform energy taken in by electrical transmission at the average rate 2.50 W. The politician gives a speech in which he complains that, at today’s electrical rates, the nation is losing $100 million every year to operate these clocks.arrow_forwardA biophysics experiment uses a very sensitive magnetic field probe to determine the current associated with a nerve impulse traveling along an axon. If the peak field strength 1.0 mm from an axon is 8.0 pT, what is the peak current carried by the axon?arrow_forward
- A closed curve encircles several conductors. The line integral PB.dL around this curve is 3,83x104 T.m (a) What is the net current in the conductors? (b) If you were to integrate around the curve in the opposite direction, what would be the value of the line integral? Select one: lenci=D 305 A, 0.0 T.m lencl = 502 A, -3.83 x 10 4T.m lenci = 502 A, -7.66 x 104 T.m lencl = 600 A, -7.66 x 104T.m lencl = 305 A, -3.83 x 10 4 T.m lencl = 502 A, 0.0 T.m %3Darrow_forwardA 0.68 T magnetic field is applied to a paramagnetic gas whose atoms have an intrinsic magnetic dipole moment of 1.3 x 1024 J/T. At what temperature will the mean kinetic energy of translation of the atoms equal the energy required to reverse such a dipole end to end in this magnetic field? Number i Unitsarrow_forwardTwo circular loops of wire surround an insulating rod as inFigure P20.53. Loop 1 carries a current I in the clockwise directionwhen viewed from the left end. If loop 1 moves towardloop 2, which remains stationary, what is the direction of theinduced current in loop 2 when viewed from the left end?arrow_forward
- The figure below is a cross-sectional view of a coaxial cable. The center conductor is surrounded by a rubber layer, an outer conductor, and another rubber layer. In a particular application, the current in the inner conductor is I₁ = 1.20 A out of the page and the current in the outer conductor is I2 = 2.96 A into the page. Assuming the distance d = 1.00 mm, answer the following. I X 1₂ (a) Determine the magnitude and direction of the magnetic field at point a. magnitude μT direction to the left (b) Determine the magnitude and direction of the magnetic field at point b. μT magnitude direction into the pagearrow_forwarda. Consider the points a and b shown. Is the potential difference ΔVab between points a and b zero? If so, why? If not, which point is more positive?b. If a wire is connected between points a and b, does it carry a current?If so, in which direction—to the right or to the left? Explain.arrow_forwardFigure P19.64 is a setup that can be used to measuremagnetic fields. A rectangular coil of wire contains N turnsand has a width w. The coil is attached to one arm of a balanceand is suspended between the poles of a magnet. The fieldis uniform and perpendicular to the plane of the coil. Thesystem is first balanced when the current in the coil is zero.When the switch is closed and the coil carries a current I, amass m must be added to the right side to balance the system.(a) Find an expression for the magnitude of the magneticfield and determine its direction. (b) Why is the result independentof the vertical dimension of the coil? (c) Supposethe coil has 50 turns and width of 5.0 cm. When the switch is closed, the coil carries a current of 0.30 A, and a mass of 20.0 gmust be added to the right side to balance the system. What isthe magnitude of the magnetic field?arrow_forward
- Physics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning