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PHYS Study Questions

# PHYS Study Questions - The diagram below shows the wave...

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Unformatted text preview: The diagram below shows the wave crests for two sources that are totally out of phase. For each of the labeled points, determine whether the light intensity (not the wave amplitude) is a minimum or a maximum. Solution: The light intensity (i.e., the brightness) will be largest wherever there is constructive interference, and smallest wherever there is destructive interference. Point C in the diagram is located where wave crests from both sources overlap, so this will be an intensity maximum. Point B will also be an intensity maximum, because it sits where the wave troughs overlap. (This is why the problem warned about using intensity rather than amplitude.) At point A, the crest from source 2 overlaps a trough from source 1, resulting in destructive interference and thus an intensity minimum. Note that this diagram is a snapshot of one instant in time as the waves move outward from the sources. One-half period after this instant, point B will see two crests and point C will see two troughs, and they will thus still be locations of constructive interference. The headlights of a pickup truck are 1.32 m apart. What is the greatest distance at which these headlights can be resolved as separate points of light on a photograph taken with a camera whose aperture has a diameter of 12.5 mm? (Take A = 555 am.) Solution: Picture the Problem: Light that has a wavelength ot‘SSS nm passes through the Iii-mm apenure ol'a camera from two headlights that are |.33 m apart. Strategy: Solve equation 38- H for the minimum resolution angle for the given wavelength and aperture sue. then use equation 28-3 to calculate the maximum distance ti.) at which the two headlights can be resolved. -' A, , I 555 nm 1 1 . - . '. t . . I' ‘ '"tli‘: U_ :_'im I! }_-5]|'| ‘ ‘lUiUJlU holutlon. l. { aILulate the resolullutl d a L ....1 ‘I 1‘ D- \ 115 mm J 2. IL‘aleulate the maximum distance to the lights: t' — t'. lanHmm I, _ .t' _ L33 I11 : tan Hm... _ [an “.003 It)“ Insight: the ear must he about IS. miles away belin'e the headlights appear to merge. Ihis. ot course. ts the ideal cane. lo the real world. the ﬁnite size ol‘the headlights and atmospheric distortions greatly reduce this maumum tllﬁtaltlue. A diﬂi'aetion grating has 2200 linestem. What is the angle between the ﬁrst—order maxima for red light (it. = 53!] um} and blue light (.3. = 4H]I run)? Solution: F'H'IIHI.‘ [ht l'ruhlrm: HE": l'llliln'l'iilll mild hILIL-I-llll lll.'ll ligltl “air- Ema- |l'-r-.-I |__!- I Flcllll": 't'tiln :'_"l| lll‘lt't- .'lll “Hum: ‘t-Il- tetra-I‘— IIII "H II': I--r tr!-.- .Illj. -t.-- --I l'::: Iir~I-.'-rt|et mat -Ir-.! a: 1'..'l|.-" '-'-.|'-I.'l.'llt_'|l'| lHui-ante". the hIIIL'viHLJIL' IIKIIIIEll“.-I'.'.1II.Lll‘:L-IltlilIl—IIIIL-wllrli'r1'::l-I_'IIﬁ||:'ll_"‘- E|n_ ~1||l xl'lJL'llll; _J' o- l|.t_ |"-. um;--l|I1|_'I|lIIIIl1urn| |.r|e'- [IL-r LII. ". I.” .- hululhrni l.H.I-'Lt.'t.'t|II.Jt.I.'II3li-Itt-Inr -' u. 5:” — _-.n. |--_-‘. .u. 1.lII--.'Ir||u. ultrlrugllllll lI_'.JIi__||lI t'J win |:i§::lll .._'||I||"t:-:II.'1|1||I lit- J. |I----.!I I|.:. n.t~e|-.-Itg:|- III bite |:-,|t: I'l_~ win III-22"“ th' i--|'.': -In I 52 -l-.L .:|t. .i.l.|.'lll._'q,|lll|._'l|t.llt.|.'Illﬂllyt't- I'-'_. |'-'.__ 'i" 5.1 - lﬂil'ﬂl'l'liﬂilc'flllll'kll'ﬂ'lilllllrlflllllu'Illlr7.I..,lII"i\$5.1!I"-|J:|.IIIIHII-lul::_'ll1d'll'l.._'rl,‘.' .‘mrl-tl||1|--.rtt-._'||'III'I Ia:|||1'.-t-'lt.ti...- I- ran 'Illi'll |l:t' e'erllml lFli'ltlJrlLll1'-..|'I-."\- Il'||_' l'I|;.L' cad -.t: |I|u afouL'lruuL ...
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PHYS Study Questions - The diagram below shows the wave...

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