Concept explainers
(a)
The direction at which the wire resting on two parallel horizontal rails would accelerate due to a magnetic field

Answer to Problem 72QAP
The force on the wire due to the magnetic force will point towards the right and hence the wire will accelerate to the right.
Explanation of Solution
Given:
A steady current of 100 A passes through a wire (of weight m=40 g=0.040 kg; length = 0.8 m) that can slide on two parallel, horizontal
Formula used:
Right hand rule for the field directionIf you point your right thumb in the direction of the current and curl your fingers, the magnetic field curls around the field lines in the direction of the curled fingers of your right hand.
Calculation:
Application of the right-hand rule will give the direction of magnetic force on the wire that is initially at rest on two parallel conducting rails.
Conclusion:
The force on the wire due to the magnetic force will point towards the right and hence the wire will accelerate to the right.
(b)
The magnetic force on the wire that rests on two parallel, horizontal conducting rails.

Answer to Problem 72QAP
The magnetic force on the wire = 100 N (rounded to one significant figure)
Explanation of Solution
Given:
A steady current of 100 A passes through a wire (of weight m=40 g=0.040 kg; length = 0.8 m) that can slide on two parallel, horizontal conducting rails. A uniform magnetic field with a magnitude of 1.2 T is directed into the page.
Formula used:
The magnitude of the magnetic force acting on the wire due to a magnetic field is given by the following equation
Calculation:
The angle between the magnetic field and the force is 90 degrees as they are perpendicular to each other. Substituting the values to equation (a);
Conclusion:
The magnetic force on the wire = 100 N (rounded to one significant figure)
(c)
How long must the rails be of the wire starting from rest is to reach a speed of 200 m/s.

Answer to Problem 72QAP
The length of the rails to facilitate wire reaching a speed of 200 m/s= 8 m
Explanation of Solution
Given:
A steady current of 100 A passes through a wire (of weight m=40 g=0.040 kg; length = 0.8 m) that can slide on two parallel, horizontal conducting rails. A uniform magnetic field with a magnitude of 1.2 T is directed into the page.
Also, from the part b) above we have calculated the magnitude of magnetic force on the wire to be 96 N.
Formula used:
Calculation:
One can determine the direction of the magnetic force using the right hand rule as mentioned in part a).Assuming that the magnetic force is the only force that is acting on the wire along the horizontal direction(x direction), the wire would undergo constant acceleration towards x direction. Hence one could apply equation (b) to the motion of the wire;
Applying this result to (c)
Conclusion:
The length of the rails to facilitate wire reaching a speed of 200 m/s= 8 m
(d)
What would be the direction of the movement of the wire if the magnetic field was directed out of the page

Answer to Problem 72QAP
If the magnetic field is directed out of the page, force on the wire due to the magnetic field would point to the left and the wire would accelerate in that direction. The numerical value of the magnetic force would be the same as calculated in part b).
Explanation of Solution
Given:
A steady current of 100 A passes through a wire (of weight m=40 g=0.040 kg; length = 0.8 m) that can slide on two parallel, horizontal conducting rails. A uniform magnetic field with a magnitude of 1.2 T is directed out of the page.
Formula used:
Right hand rule for the field directionIf you point your right thumb in the direction of the current and curl your fingers, the magnetic field curls around the field lines in the direction of the curled fingers of your right hand
Calculation:
Application of the right hand rule would give the direction of movement of the wire.
Conclusion:
If the magnetic field is directed out of the page, force on the wire due to the magnetic field would point to the left and the wire would accelerate in that direction. The numerical value of the magnetic force would be the same as calculated in part b).
(e)
What would be the direction of the movement of the wire if the magnetic field was directed towards the top of the page

Answer to Problem 72QAP
If the magnetic field is directed towards to the top of the page the magnetic force on the wire would be zero because the current and the magnetic field would be antiparallel to each other.
Explanation of Solution
Given:
A steady current of 100 A passes through a wire (of weight m=40 g=0.040 kg; length = 0.8 m) that can slide on two parallel, horizontal conducting rails. A uniform magnetic field with a magnitude of 1.2 T is directed out of the page.
Formula used:
Right hand rule for the field directionIf you point your right thumb in the direction of the current and curl your fingers, the magnetic field curls around the field lines in the direction of the curled fingers of your right hand
Calculation:
The magnetic field and the current must not be antiparallel to facilitate a movement of the wire.
Conclusion:
If the magnetic field is directed towards to the top of the page the magnetic force on the wire would be zero because the current and the magnetic field would be antiparallel to each other
Want to see more full solutions like this?
Chapter 19 Solutions
COLLEGE PHYSICS LL W/ 6 MONTH ACCESS
- How, Please type the whole transcript correctly using comma and periods as needed. I have uploaded the picture of a video on YouTube. Thanks,arrow_forwardA spectra is a graph that has amplitude on the Y-axis and frequency on the X-axis. A harmonic spectra simply draws a vertical line at each frequency that a harmonic would be produced. The height of the line indicates the amplitude at which that harmonic would be produced. If the Fo of a sound is 125 Hz, please sketch a spectra (amplitude on the Y axis, frequency on the X axis) of the harmonic series up to the 4th harmonic. Include actual values on Y and X axis.arrow_forwardSketch a sign wave depicting 3 seconds of wave activity for a 5 Hz tone.arrow_forward
- Sketch a sine wave depicting 3 seconds of wave activity for a 5 Hz tone.arrow_forwardThe drawing shows two long, straight wires that are suspended from the ceiling. The mass per unit length of each wire is 0.050 kg/m. Each of the four strings suspending the wires has a length of 1.2 m. When the wires carry identical currents in opposite directions, the angle between the strings holding the two wires is 20°. (a) Draw the free-body diagram showing the forces that act on the right wire with respect to the x axis. Account for each of the strings separately. (b) What is the current in each wire? 1.2 m 20° I -20° 1.2 marrow_forwardplease solve thisarrow_forward
- please solve everything in detailarrow_forward6). What is the magnitude of the potential difference across the 20-02 resistor? 10 Ω 11 V - -Imm 20 Ω 10 Ω 5.00 10 Ω a. 3.2 V b. 7.8 V C. 11 V d. 5.0 V e. 8.6 Varrow_forward2). How much energy is stored in the 50-μF capacitor when Va - V₁ = 22V? 25 µF b 25 µF 50 µFarrow_forward
- 9). A series RC circuit has a time constant of 1.0 s. The battery has a voltage of 50 V and the maximum current just after closing the switch is 500 mA. The capacitor is initially uncharged. What is the charge on the capacitor 2.0 s after the switch is closed? R 50 V a. 0.43 C b. 0 66 C c. 0.86 C d. 0.99 C Carrow_forward1). Determine the equivalent capacitance of the combination shown when C = 12 pF. +11/20 2C C Carrow_forward3). When a capacitor has a charge of magnitude 80 μC on each plate the potential difference across the plates is 16 V. How much energy is stored in this capacitor when the potential difference across its plates is 42 V? a. 1.0 mJ b. 4.4 mJ c. 3.2 mJ d. 1.4 mJ e. 1.7 mJarrow_forward
- Glencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-HillPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
- College PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax CollegePhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningPhysics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning





