This preview shows pages 1–2. 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: Kapoor (mk9499) homework27 Turner (60230) 1 This printout should have 12 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A small aircore solenoid has a length of 1 cm and a radius of 0 . 17 cm. The permeability of free space is 1 . 25664 10 6 N / A 2 . If the inductance is to be 0 . 47 mH, how many turns per centimeter (whole turns plus fractional turns) are required? Correct answer: 641 . 83 turns / cm. Explanation: Let : = 1 cm = 0 . 01 m , = 1 . 25664 10 6 N / A 2 , r = 0 . 17 cm = 0 . 0017 m , and L = 0 . 47 mH = 0 . 01 m . Let n be the number of turns per centimeter. The area is A = r 2 = (0 . 0017 m) 2 = 9 . 0792 10 6 m 2 . The inductance of the aircore solenoid is L = n 2 A n 2 = L A = 1 1 . 25664 10 6 N / A 2 . 00047 H (9 . 0792 10 6 m 2 )(0 . 01 m) = 4 . 11946 10 9 (turns / m) 2 Therefore, n = radicalBig 4 . 11946 10 9 (turns / m) 2 = 64183 turns / m = 641 . 83 turns / cm . 002 10.0 points An emf of 57 mV is induced in a 494turn coil when the current is changing at a rate of 11 . 5 A / s. What is the magnetic flux through each turn of the coil at an instant when the current is 2 . 94 A? Correct answer: 2 . 94983 10 5 T m 2 . Explanation: Let : E = 57 mV = 0 . 057 V , N = 494 , I = 2 . 94 A , and I t = 11 . 5 A / s . From Faradays Law E = N t = L I t E = L I t L = E I t = . 057 V 11 . 5 A / s = 0 . 00495652 H At the instant where the current is 2 . 94 A , the flux through each turn is = L I N = (0 . 00495652 H) (2 . 94 A) 494 = 2 . 94983 10 5 T m 2 . keywords: 003 (part 1 of 3) 10.0 points One application of an RL circuit is the gen eration of timevarying highvoltage from a lowvoltage source, as shown in the figure....
View
Full
Document
This note was uploaded on 06/28/2009 for the course PHY 303L taught by Professor Turner during the Fall '08 term at University of Texas at Austin.
 Fall '08
 Turner
 Physics, Work

Click to edit the document details