Physics for Scientists and Engineers with Modern Physics
4th Edition
ISBN: 9780131495081
Author: Douglas C. Giancoli
Publisher: Addison-Wesley
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Textbook Question
Chapter 29, Problem 44P
(II) The back emf in a motor is 85 V when the motor is operating at 1100 rpm. How would you change the motor’s magnetic field if you wanted to reduce the back emf to 75 V when the motor was running at 2300 rpm?
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Physics for Scientists and Engineers with Modern Physics
Ch. 29.1 - Return to the Chapter-Opening Question, page 758,...Ch. 29.2 - Prob. 1BECh. 29.3 - In what direction will the electrons now in Fig....Ch. 29.5 - A bicycle headlight is powered by a generator that...Ch. 29.7 - Prob. 1EECh. 29 - Prob. 1QCh. 29 - What is the difference between magnetic flux and...Ch. 29 - Suppose you are holding a circular ring of wire...Ch. 29 - Prob. 4QCh. 29 - Is there a force between the two loops discussed...
Ch. 29 - Suppose you are looking along a line through the...Ch. 29 - The battery mentioned in Question 6 is...Ch. 29 - Prob. 8QCh. 29 - Prob. 9QCh. 29 - In situations where a small signal must travel...Ch. 29 - What is the advantage of placing the two insulated...Ch. 29 - Prob. 12QCh. 29 - A region where no magnetic field is desired is...Ch. 29 - A cell phone charger contains a transformer. Why...Ch. 29 - An enclosed transformer has four wire leads coming...Ch. 29 - The use of higher-voltage lines in homessay, 600 V...Ch. 29 - Prob. 17QCh. 29 - Prob. 18QCh. 29 - Prob. 19QCh. 29 - Will an eddy current brake (Fig. 2921) work on a...Ch. 29 - It has been proposed that eddy currents be used to...Ch. 29 - The pivoted metal bar with slots in Fig. 2935...Ch. 29 - If an aluminum sheet is held between the poles of...Ch. 29 - A bar magnet falling inside a vertical metal tube...Ch. 29 - A metal bar, pivoted at one end, oscillates freely...Ch. 29 - Since a magnetic microphone is basically like a...Ch. 29 - Prob. 1PCh. 29 - (I) The north pole of the magnet in Fig. 2936 is...Ch. 29 - Prob. 3PCh. 29 - (I) A 22.0-cm-diameter loop of wire is initially...Ch. 29 - Prob. 5PCh. 29 - (II) A 10.8-cm-diameter wire coil is initially...Ch. 29 - (II) A 16-cm-diameter circular loop of wire is...Ch. 29 - (II) (a) If the resistance of the resistor in Fig....Ch. 29 - Prob. 9PCh. 29 - (II) The magnetic field perpendicular to a...Ch. 29 - (II) A circular loop in the plane of the paper...Ch. 29 - (II) Part of a single rectangular loop of wire...Ch. 29 - (II) While demonstrating Faradays law to her...Ch. 29 - Prob. 14PCh. 29 - (II) A 22.0-cm-diameter coil consists of 28 turns...Ch. 29 - (II) A power line carrying a sinusoidally varying...Ch. 29 - (II) The magnetic field perpendicular to a single...Ch. 29 - Prob. 18PCh. 29 - (II) A 25-cm-diameter circular loop of wire has a...Ch. 29 - (II) The area of an elastic circular loop...Ch. 29 - Prob. 21PCh. 29 - Prob. 22PCh. 29 - Prob. 23PCh. 29 - (II) Inductive battery chargers, which allow...Ch. 29 - Prob. 25PCh. 29 - Prob. 26PCh. 29 - (I) The moving rod in Fig. 2912b is 13.2 cm long...Ch. 29 - (I) The moving rod in Fig. 2912b is 12.0 cm long...Ch. 29 - Prob. 29PCh. 29 - (II) If the U-shaped conductor in Fig. 2912a has...Ch. 29 - (II) Suppose that the U-shaped conductor and...Ch. 29 - (II) When a car drives through the Earths magnetic...Ch. 29 - Prob. 33PCh. 29 - Prob. 34PCh. 29 - (III) A short section of wire, of length a, is...Ch. 29 - (I) The generator of a car idling at 875-rpm...Ch. 29 - Prob. 37PCh. 29 - (II) A simple generator has a 480-loop square coil...Ch. 29 - (II) Show that the rms output of an ac generator...Ch. 29 - (II) A 250-loop circular armature coil with a...Ch. 29 - Prob. 41PCh. 29 - (I) A motor has an armature resistance of 3.05 ....Ch. 29 - (II) What will be the current in the motor of...Ch. 29 - (II) The back emf in a motor is 85 V when the...Ch. 29 - Prob. 45PCh. 29 - (I) A transformer has 620 turns in the primary...Ch. 29 - (I) Neon signs require 12 kV for their operation....Ch. 29 - (II) A model-train transformer plugs into 120-V ac...Ch. 29 - (II) The output voltage of a 75-W transformer is...Ch. 29 - (II) If 65 MW of power at 45 kV (rms) arrives at a...Ch. 29 - Prob. 51PCh. 29 - (III) Design a dc transmission line that can...Ch. 29 - (III) Suppose 85 kW is to be transmitted over two...Ch. 29 - Prob. 54PCh. 29 - (II) The betatron, a device used to accelerate...Ch. 29 - (III) Show that the electrons in a betatron,...Ch. 29 - (III) Find a formula for the net electric field in...Ch. 29 - Prob. 58GPCh. 29 - A square loop 27.0 cm on a side has a resistance...Ch. 29 - Power is generated at 24 kV at a generating plant...Ch. 29 - Prob. 61GPCh. 29 - Prob. 62GPCh. 29 - A pair of power transmission lines each have a...Ch. 29 - Show that the power loss in transmission lines,...Ch. 29 - A high-intensity desk lamp is rated at 35 W but...Ch. 29 - Prob. 66GPCh. 29 - A coil with 150 turns, a radius of 5.0 cm, and a...Ch. 29 - A search coil for measuring B (also called a flip...Ch. 29 - A ring with a radius of 3.0 cm and a resistance of...Ch. 29 - A flashlight can be made that is powered by the...Ch. 29 - A small electric car overcomes a 250-N friction...Ch. 29 - What is the energy dissipated as a function of...Ch. 29 - A thin metal rod of length rotates with angular...Ch. 29 - The magnetic field of a shunt-wound dc motor is...Ch. 29 - Prob. 75GPCh. 29 - A circular metal disk of radius R rotates with...Ch. 29 - What is the magnitude and direction of the...Ch. 29 - Prob. 78GPCh. 29 - Prob. 79GPCh. 29 - Prob. 80GP
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