HW11B_Sol_20_F11

HW11B_Sol_20_F11 - o:t-a COUNTRY HOMEWORK SET 11 or are...

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Unformatted text preview: o:t.-. '-.-a:.;.!:. COUNTRY HOMEWORK SET 11 or: are; consent Phys 2114- Instructor: Professor Bandy Fall 2011 1. When you look at the North Star (Polaris), you intercept light from a S’th at a distance of 43] [y and emitting energy at a rate of 2.2 x 103 times that of our Sun (PM = 3.90 x 1026 W). Neglecting atmospheric absmph'on, ﬁnd the rms values of the electric and magneti ﬁelds when the starlight reaches the Earth. Note: A light-year ﬂy) is the distance that limit, traveling through a vacuum with speed of 186,000 or 2.998 x lOsmfs, would corner in 1.0 year. 2. a. A radio wave is traveling in the —}' direction. What is the direction tr E at a point where E is in the +i direction? _ b. Show that the quantity CB has the same units as E and that the Poynting vector has units PIC/m2. 3. Figure 1 shows a vertically polarized radio wave of frequency, 10 ><10ﬁ Hz , traveling into the page. The maximum electric ﬁeld strength is 1000 War. What are: a. the maximum 111 etic ﬁeld strength? I). The magnetic ﬁeld strength and direction at a point where E =500V1l m, down. c. The Smallest distanCe betWeen a point on the wave having the magnetic ﬁeld of part b and a point where the magnetic ﬁeld is at maximum strength? a. Assume that a 100 W light bulb radiates all its energy as a single wavelength of visible light. ‘ Estimate the electric and magnetic ﬁeld strength at the surface of the nth. b. The intensity of sunlight reaching the earth is I 3 60 Wmi what are the power output of the sun and the intensity of sunlight on Mars? c. Assuming all the sunlight is absorbed, what is the radiation- Iressme force on the earth? Give your answer in Newtans and as a percentage of the sun’s gravitational nice on the earth. 5. a. Assuming laser pointer delivers 01 0-mW average power in a beam 0.90 mm in diameter, what is the average intensity, and peak electric ﬁeld and peak magnetic ﬁeld strengths. b. Assuming 1.04kW—radio transmitter broadcasts uniformly in all directions, what is the intensity of its signal at a distance of 5.0 km from the transmitter? ~ 6. 1A1} 80 kg astronaut has gone outside his spaCe capSUle without his safety tether, and he has drifted 5.0 m away from the capsule. He has howeVer, a J 000 Wportable laser that can Operate for 1 hr. If he ﬁres the laser in the opposite direction accelerating his body toward the capsule, can he make it back? Assume he has a 10—hr supply of oxygen. @l a. Unpolarized light of intensity [0 is incident on three polarizing ﬁlters. The axis of the ﬁrst is vertical, . that of the second is 45" from the vertical, and that of the third is horizontal. What light intensity emerges from the third ﬁlter? I). A polarizer blocks 75 % of a polariged light beam. Find the angle between the bearn’s polarization and polarizer’s axis? 8. A narrow column of air is found to have standing waves at frequencies pf 390 Hz, 520 Hz, and 65 0 Hz and at no frequencies in between these. The behavior of the tub at frequencies less than 390 Hz or greater than 650 Hz is not known. a. is this an Open-open tube or an open—closed tube? y Explain. b. How long is the tube? F 9.‘ The index of reﬂection of bermene is 1.8. Calculate the critical angle for a light E" ray traveling in benzene toward a ﬂat layer of air above the benzene. @npolarized light of intensity 10 mW/m2 is sent into a vertical polarizing sheet. Find - a. the amplitude of the electric ﬁeld component of the transmitted light land b. the radiation pressure on the sheet due to its absorbing some of the light? Figure 1 c 2‘ yiiﬁ‘fn' (CM ﬁe; V Z 3 3. 5 5 K/A A it» K _ Q :- ‘F" air-zinxklhcéfé _/ gigs? A! {F‘ I ‘ ‘ a; {,I :‘ ;- 0 J\( v! ’— W «I t r I, F! 5: M f Ff L‘ D lit—‘2' -' ‘ . I" ’ .- :-rnw:€ r T“ I... J: ff A! 1"» :2 )2 W 9 RE! " n 41:! -— L'ffr 2. X it) wry/14:13?- WW, QW’JTQJ q v“ a a _ -"J'V{ *4 \$— PM" i? :.- pg“ # ‘2 :"f f. .S' X36) ‘LM/ {K i- : anﬁu J z} IQ q ’ (5 ’f/Vv—JEJJEL) VHF. - I :- lv H . . D J 77 ‘ {f M ’ 4. . ‘ '2; F, F"! I 2 h I; m w I.“ {‘37: (1 cl,- __ [#3 P: :2 CL 7;. ’1‘,“ f?“ n C) 4 J’JWIV 1/4 ( . . ,, M. i _ 2 . .. , M,“ LU” W km“ a) 62 MD To Gm => (5 —0127;«.». a Lmd m1.) I - .s {In 31- r-‘ wrfx/LﬁMka-J _L_ “fi- :-.'_-ﬁ Iv r, r .a; K! ‘1 ‘ t; W, H q 7 ﬁ 1 '3. if. .11 z’uayrc fl: '5:- Mi; A I Ch I x i M; L; 9 / - W E H I r M . Kl! ._ , ‘ ' 3 a “T. H ‘2 b If: ; ..‘ - . 4 - 4 7 :2 Mae 1 A H. q ___7 1' {1‘ gm: 12,; Anna/2 (atst u - 7* ,, .3 PM L; .91 h s. . ‘1 ".J F n. "‘9: a, ) 2' ‘H. {E ‘. 5 1:- I! ’1‘; 3 55 x 5 1 ‘5‘ u W: ._L ...
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HW11B_Sol_20_F11 - o:t-a COUNTRY HOMEWORK SET 11 or are...

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