PHY 114 A General Physics II 11 AM-12:15 PM TR Olin 101

Transcription

1 PHY 4 A Geeral Physcs II AM-:5 PM TR Ol Pla or Lecture 9 (Chapter 36): Optcal propertes o lght. Mrror relectos. Images lat ad sphercal mrrors 4/4/ PHY 4 A Sprg -- Lecture 9

2 4/4/ PHY 4 A Sprg -- Lecture 9

3 Plae wave soluto to Maxwell s equatos delectrc medum wth vc/: B y z B z y ( x, t) ( x, t) v max max ( k( x vt) ) ( k( x vt) ) Addtoal commets: For ths soluto, the y drecto s called the polarzato drecto (the eld oretato) Ths s a perodc wave, where kπ/λ ad λ represets the wavelegth ad the requecy o the wave s kc/ωπ. 4/4/ PHY 4 A Sprg -- Lecture 9 3

4 Idex o reracto : I vacuum: ε µ c ε µ I medum : ε ε µ µ v εµ c 4/4/ PHY 4 A Sprg -- Lecture 9 4

5 ω s c ω s c ad B cotuous at boudary B y z B z y ( x, t) ( x, t) max ω c ( x ct) ( / c) ( x ct) max ω c Sell's law : s s 4/4/ PHY 4 A Sprg -- Lecture 9 5

6 4/4/ PHY 4 A Sprg -- Lecture 9 6 Geeral case relecto ad reracto For R + + scatterg plae polarzed out o For polarzed scatterg plae For R R / ad / the :, I R

7 Images ormed rom relected lght: Notato or mage posto: q object vrtual mage deal surace 4/4/ PHY 4 A Sprg -- Lecture 9 7

8 Aalyss o mrror mage Mrror symmetry: Usg geometry: p hh' 4/4/ PHY 4 A Sprg -- Lecture 9 8

9 Termology: Vrtual mage -- perceved mage but o lght ca be detected at the locato o the vrtual mage Real mage - - lght ca detected at the locato o the real mage 4/4/ PHY 4 A Sprg -- Lecture 9 9

10 vrtual mage object 4/4/ PHY 4 A Sprg -- Lecture 9

11 Summary o geometrc optcs o plae mrror vrtual mage I ths case : p; Geeral equato descrbg object ad mage postos: Mrror equato : + p 4/4/ PHY 4 A Sprg -- Lecture 9

12 Aalyss o mage rom plae mrror Some detals: (vrtual) By coveto, < or vrtual mage Geometrcal relatoshps p hh + p Magcato M Image heght Object heght h h 4/4/ PHY 4 A Sprg -- Lecture 9

13 Sphercal mrrors -- cocave Relecto o parallel lght rays: Detal ½ R R 4/4/ PHY 4 A Sprg -- Lecture 9 3

14 4/4/ PHY 4 A Sprg -- Lecture 9 4

15 Why does ths satelltedsh look lke a cocave mrror? A. Because t s. B. It does t ot shy eough. Where s the receve placed relatve to the radus o curvature R? A. Placed at R. B. Placed at R/. 4/4/ PHY 4 A Sprg -- Lecture 9 5

16 Image ormed cocave mrror: Plae mrror: p -q + p h M h p xample: 4 cm p cm -.33 cm M p /4/ PHY 4 A Sprg -- Lecture 9 6

17 4/4/ PHY 4 A Sprg -- Lecture 9 7 p - Proo o mrror equato: h h Smlar tragles: p h h Smlar tragles: p h h h h p +

18 Image ormed by cocave mrror: p - Geeral result or vrtual mage ormed by cocave mrror p < mage s uprght ad creased sze 4/4/ PHY 4 A Sprg -- Lecture 9 8

19 4/4/ PHY 4 A Sprg -- Lecture 9 9

20 Image ormed by cocave mrror: xample: 4 cm p cm p 6.67 cm M p p + M h h p 4/4/ PHY 4 A Sprg -- Lecture 9

21 4/4/ PHY 4 A Sprg -- Lecture 9

22 Image ormed by cocave mrror: p Geeral result or real mage ormed by cocave mrror p > mage s upsde dow Is mage always reduced sze? (A) yes (B) o 4/4/ PHY 4 A Sprg -- Lecture 9

23 Covex mrror 4/4/ PHY 4 A Sprg -- Lecture 9 3

24 Image ormed by covex mrror: p - xample: -4 cm p 6 cm -3. cm + p h M h p - M p Geeral result or vrtual mage ormed by covex mrror: mage s uprght ad decreased sze 4/4/ PHY 4 A Sprg -- Lecture 9 4

25 Ca the mage ormed by a covex mrror ever be creased sze ( M >)? (A) yes (B) o Is t possble to orm a real mage wth a covex mrror? (A) yes (B) o 4/4/ PHY 4 A Sprg -- Lecture 9 5

26 4/4/ PHY 4 A Sprg -- Lecture 9 6

27 Covex mrror used or survellace: 4/4/ PHY 4 A Sprg -- Lecture 9 7

28 Suppose that you were behd the steerg wheel ad saw ths mage your rear-vew mrror. Whch o these s lkely to be true? A. The truck s closer to you tha t appears. B. The truck s urther rom you tha t appears. C. Do t chage laes just case. 4/4/ PHY 4 A Sprg -- Lecture 9 8