3. Preflight 15.1, 15.2 1 2 3 “ In order to find the loop that dectects the electromagnetic wave, we should find the loop that has the greatest flux through the loop.” x z y E B loop in xy plane loop in xz plane loop in yz plane
4.
5.
6. Preflight 15.4 Suppose that the electric field of an electromagnetic wave decreases in magnitude. The magnetic field: 1 increases 2 decreases 3 remains the same E=cB
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22. Law of Malus – 2 Polarizers Cool Link 1) Intensity of unpolarized light incident on linear polarizer is reduced by ½ . S 1 = ½ S 0 S = S 0 S 1 S 2 2) Light transmitted through first polarizer is vertically polarized. Angle between it and second polarizer is =90º. S 2 = S 1 cos 2 (90º) = 0 Example
23. How do polaroid sunglasses work? incident light unpolarized reflected light partially polarized the sunglasses reduce the glare from reflected light
24.
25. Law of Malus – 3 Polarizers 2) Light transmitted through first polarizer is vertically polarized. Angle between it and second polarizer is =45º. I 2 = I 1 cos 2 (45º) = ½ I 0 cos 2 (45º) 3) Light transmitted through second polarizer is polarized 45º from vertical. Angle between it and third polarizer is =45º. I 3 = I 2 cos 2 (45º) I 2 = I 1 cos 2 (45) = ½ I 0 cos 4 (45º) = I 0 /8 I 1 = ½ I 0 Example
26. ACT: Law of Malus A B 1) S 2 A > S 2 B 2) S 2 A = S 2 B 3) S 2 A < S 2 B S 1 = S 0 cos 2 (60) S 2 = S 1 cos 2 (30) = S 0 cos 2 (60) cos 2 (30) S 1 = S 0 cos 2 (60) S 2 = S 1 cos 2 (60) = S 0 cos 4 (60) Cool Link E 0 E 0 TA TA S 1 S 2 S 0 TA TA S 1 S 2 S 0
27.
Editor's Notes
1
Note wavelength must be much large than loop size Radio waves: 3 meters Demo 158
Note E=cB is only true for EM wave, not in general
Again note energy density is same only for EM wave, not in general
Again note energy density is same only for EM wave, not in general
![Today: Electromagnetic Waves ,[object Object],[object Object],[object Object]](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)