1
Quiz 2 solutions are in order of the questions for version A.
(1). Correct answer A
The intensity equals
E 2
2 µ
0 c
(5000) 2
=
2(4 π × 10 − 7 )(3 × 10 8 )
' 33 kW
(2). Correct answer is C
As the mirror rotates, the ray rotates by exactly twice the mirror rotation angle.
(easiest way to see this is to consider what happens if you rotate the mirror by 90 o .
Hence the answer is C
(3). Correct answer is C
The critical angle here is asin (1/1.37) = 46.88
o . To get this angle incident on the side of the fiber, we need angle of refraction for the incoming ray of 43.12
o
. This then requires that the incoming ray have an angle of asin(1.37 sin (43.12
o )) which gives result C
(4). Correct answer is A
From the first refraction we can determine that n glass sin 65 o
= 1 .
33 sin 48 o
We can then use this for the second refraction to find the new angle
(5). Correct answer is C
Because of the fact that the rays refract away from the normal as they exit the water, the fish appears to be shallower than it actually is. Hence the answer must be C
(6). Correct answer is B
B max
= E max
/c
(7). Correct answer is B
The intensity equals
E 2
I =
2 µ
0 c
P
=
4 πR 2
Plugging in all the numbers gives P=1500 W.

2
(8). Correct answer is C
Going through the first filter reduces the intensity by .5 and going through the second by cos 2 θ . Setting this equal to .37 gives result C
(9). Correct answer is B
Going from one medium to another does not change the frequency; since the speed changes, the wavelength must also change
(10). Correct answer is E
Plane mirrors have an image that is always the same size as the object.