Lemuel physics 2 1

Lemuel physics 2 1 - Wong, Lemuel – Homework 1 – Due:...

Info iconThis preview shows pages 1–3. 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: Wong, Lemuel – Homework 1 – Due: Jan 26 2007, 11:00 pm – Inst: Matt Mackie 1 This print-out should have 24 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. Note: HW is due 11pm central time, which is midnight out time. 001 (part 1 of 2) 10 points A certain blue-green light has a wavelength of 580 nm in air. What is its wavelength in water, where light travels at 75 % of its speed in air? Correct answer: 435 nm. Explanation: Frequency doesn’t change when light trav- els from air to water, but the speed and the wavelength do. wavelength = 0 . 75 (580 nm) = 435 nm . 002 (part 2 of 2) 10 points What is its wavelength in Plexiglas, where light travels at 67 % of its speed in air? Correct answer: 388 . 6 nm. Explanation: wavelength = 0 . 67 (580 nm) = 388 . 6 nm . keywords: 003 (part 1 of 1) 10 points The reflecting surfaces of two intersecting flat mirrors are at an angle of 59 ◦ , as shown in the figure. A light ray strikes the horizontal mirror at an angle of 51 ◦ with respect to the mirror’s surface. 59 ◦ 51 ◦ φ Figure is not drawn to scale. Calculate the angle φ . Correct answer: 62 ◦ . Explanation: Basic Concept: θ incident = θ reflected Solution: θ 1 θ 2 φ θ Figure is to scale. The sum of the angles in a triangle is 180 ◦ . In the triangle on the left we have angles θ , 180 ◦- θ 1 2 , and 180 ◦- θ 2 2 , so 180 ◦ = θ + 180 ◦- θ 1 2 + 180 ◦- θ 2 2 , or θ 1 + θ 2 = 2 θ . (1) In the triangle on the right we have angles θ 1 , θ 2 , and φ. 180 ◦ = θ 1 + θ 2 + φ, so θ 1 + θ 2 = 180 ◦- φ. (2) Combining Eq. 1 and 2, we have φ = 180 ◦- 2 θ = 180 ◦- 2(59 ◦ ) = 62 ◦ . Wong, Lemuel – Homework 1 – Due: Jan 26 2007, 11:00 pm – Inst: Matt Mackie 2 As a matter of interest, in the upper-half of the figure the angles (clockwise) in the triangles from left to right are 39 ◦ , 39 ◦ , and 102 ◦ ; 78 ◦ , 31 ◦ , and 71 ◦ ; 109 ◦ , 20 ◦ , and 51 ◦ ; 129 ◦ , 20 ◦ , and 31 ◦ ; and in the lower-half of the figure the angles (counter-clockwise) in the triangles from left to right are 20 ◦ , 20 ◦ , and 140 ◦ ; 40 ◦ , 31 ◦ , and 109 ◦ ; 71 ◦ , 39 ◦ , and 70 ◦ ; 110 ◦ , 39 ◦ , and 31 ◦ . keywords: 004 (part 1 of 2) 10 points Consider the case in which light ray A is in- cident on mirror 1 , as shown in the figure. The reflected ray is incident on mirror 2 and subsequently reflected as ray B. Let the an- gle of incidence (with respect to the normal) on mirror 1 be θ A = 35 ◦ and the point of incidence be located 20 cm from the edge of contact between the two mirrors....
View Full Document

This note was uploaded on 02/17/2011 for the course PHY 303L taught by Professor Turner during the Spring '08 term at University of Texas.

Page1 / 10

Lemuel physics 2 1 - Wong, Lemuel – Homework 1 – Due:...

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

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