This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Create assignment, 00224, Homework 8, Mar 25 at 5:26 pm 1 This print-out should have 10 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. The due time is Central time. Clockwise Current 31:01, trigonometry, multiple choice, > 1 min, fixed. 001 A circular coil of wire rests on your desk. A magnetic field is directed at right angles to the plane of your desk and passes through the coil. For a clockwise current (as you look down on your desk) to be generated, the magnetic field must be directed 1. downward toward the desk and be in- creasing in time. 2. downward toward the desk and be con- stant in time. 3. upward away from the desk and be in- creasing in time. correct 4. upward away from the desk and be con- stant in time. Explanation: If an induced emf sets up a complete cur- rent, the direction of the induced current is always such as to oppose the change in mag- netic flux that produces it. keywords: Faraday Equation 31:01, highSchool, multiple choice, < 1 min, fixed. 002 Suppose you are looking into the end of a long cylindrical tube in which there is a uniform magnetic field pointing away from you. What is the direction of the induced electric field if the magnitude of the magnetic field is decreased with time? 1. clockwise correct 2. counterclockwise 3. toward you 4. away from you 5. radially outward from the axis of the tube 6. radially inward toward the axis of the tube Explanation: If the magnetic field decreases with time, the electric field will be generated in order to oppose the change. The right hand rule can be applied to find that the direction of electric field is in the clockwise direction. keywords: Holt SF 22A 02 31:01, highSchool, numeric, > 1 min, wording- variable. 003 A coil with 205 turns of wire, a total resistance of 23 , and a cross-sectional area of 0.25 m 2 is positioned with its plane perpendicular to the field of a powerful electromagnet. What average current is induced in the coil during the 0.25 s that the magnetic field drops from 1.6 T to 0.0 T? Correct answer: 14 . 2609 A. Explanation: Basic Concepts: E =- N AB (cos ) t =- NA (cos ) B t A = r 2 I = E R Given: N = 205 R = 23 A = 0 . 25 m 2 Create assignment, 00224, Homework 8, Mar 25 at 5:26 pm 2 = 0 t = 0 . 25 s B i = 1 . 6 T B f = 0 T Solution: B = B f- B i = 0 T- 1 . 6 T =- 1 . 6 T so I =- NA (cos ) B R t =- (205) ( . 25 m 2 )...
View Full Document