Physics for Scientists and Engineers with Modern Physics
4th Edition
ISBN: 9780131495081
Author: Douglas C. Giancoli
Publisher: Addison-Wesley
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Chapter 29, Problem 65GP
A high-intensity desk lamp is rated at 35 W but requires only 12 V. It contains a transformer that converts 120-V household voltage. (a) Is the transformer step-up or step-down? (b) What is the current in the secondary coil when the lamp is on? (c) What is the current in the primary coil? (d) What is the resistance of the bulb when on?
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A transformer has 900 turns on its secondary and 100 turns on its primary. The primary is connected to a 14-V source.
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Ex.3-Cell phone charger. The charger for a cell phone contains a transformer that reduces 120-
V (or 240-V) ac to 5.0-V ac to charge the 3.7-V battery. (It also contains diodes to change the
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consider a simple transformer that has a 100 turn primary coil and a 1000 turn secondary coil. The primary is connected to 120 volts ac source and the secondary is connected to an electrical device with a resistance of 200 ohms.
what will be the voltage output of the secondary?
what current flows in the secondary circuit?
now that you know the voltage and the current, what is the power in the secondary coil?
neglecting small heating losses, and knowing that energy is conserved, what is the power in the primary coil?
now that you know the power and the voltage across the primary coil, what is the current drawn by the primary coil?
Chapter 29 Solutions
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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