# _017 - Solution for Homework 18 Inductance Solution to...

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
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Solution for Homework 18 Inductance Solution to Homework Problem 18.1(What Makes Second Speaker Work?) Problem: In lab, the second speaker we built was made with a fixed magnet and a coil attached to a vibrating board. What physical law in most important in describing the operation of this speaker? Select One of the Following: (a) Faraday’s Law. (b) Ampere’s Law (c-Answer) The Lorentz Force (d) Biot-Savart Law (e) Coulomb’s Law Solution Lorentz Force Total Points for Problem: 3 Points Solution to Homework Problem 18.2(Gauss Gun Energy) Problem: I estimate that the Gauss gun (a solenoid) is wound with 500 turns over a distance of 15cm with an average radius of 1 . 5cm . The peak current is about 300A . Calculate the energy stored in the Gauss’ gun at peak current. Use the infinite solenoid approximation. Select One of the Following: (a-Answer) 70J (b) . 01J (c) 200J (d) 6000J (e) . 3J Solution The energy stored in a magnetic field is given by U = 1 2 LI 2 where L is the self-inductance. The self-inductance of a solenoid, in the infinite solenoid approximation is, L = μ n 2 Aℓ . For the Gauss gun the turns per unit length is n = N/L = (500) / (0 . 15m) = 3333m- 1 , and the self inductance is (4 π × 10- 7 Tm A )(3333m- 1 ) 2 π (1 . 5cm) 2 (0 . 15m) = 0 . 00148H and the total energy stored in the field U = 1 2 LI 2 = 1 2 (0 . 00148H)(300A) 2 = 70J Total Points for Problem: 3 Points 1 Solution to Homework Problem 18.3(Voltage Across Commerical Inductor) Problem: Coilcraft makes a chip mount inductor with inductance 10 μ H and peak current 1 . 4A . If we power this inductor at its peak current with a signal that has the frequency of house current, the inductor carries a current of I ( t ) = 1 . 4A sin ω t where ω = 380s- 1 Compute the peak voltage across the inductor....
View Full Document

## This note was uploaded on 05/04/2008 for the course PHYS 2074 taught by Professor Stewart during the Winter '08 term at Arkansas.

### Page1 / 7

_017 - Solution for Homework 18 Inductance Solution to...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online