fall_03_exam3_sol_phy2054

Fall_03_exam3_sol_ph - Solution to Exam 3 Paul Avery Art Hebard PHY2049 Fall 2003 Nov 21 2003 1 A small transmitter in a secret location broadcasts

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Solution to Exam 3 Paul Avery, Art Hebard PHY2049, Fall 2003 Nov. 21, 2003 1. A small transmitter in a secret location broadcasts a signal uniformly in all directions with 1 W of power. If a receiving antenna can detect a minimum signal intensity of 10- 8 W / m 2 , what is the maximum distance in meters that the transmitter signal can be detected? Solution: Since the transmitter broadcasts uniformly in all directions, the intensity S at a distance d is S = P/ 4 πd 2 , where P = 1 Watt is the radiated power. Using S = 10- 8 W/m 2 yields a maximum distance of 2820 meters. 2. A solenoid with radius r and length l is wound with copper wire having a resistance of 10 Ω/m. The number of turns of wire per unit length of solenoid is n . Similar wire with the same winding density n is used to fabricate a second solenoid with twice the radius and four times the length of the first solenoid. The relaxation time of the second solenoid, L/R , is how much larger than the relaxation time of the first solenoid? Solution: The inductance is proportionate to n 2 Al , where n is the number of turns per meter, A is the area and l is the length of the solenoid. With A and l both 4 times bigger, L is 16 times bigger for the second solenoid compared to the first. The resistance R is 8 times larger (2 from radius and 4 for length), making...
View Full Document

This test prep was uploaded on 04/17/2008 for the course PHY 2054 taught by Professor Avery during the Spring '08 term at University of Florida.

Page1 / 3

Fall_03_exam3_sol_ph - Solution to Exam 3 Paul Avery Art Hebard PHY2049 Fall 2003 Nov 21 2003 1 A small transmitter in a secret location broadcasts

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online