12A Physics Light Unit practice test.
/30 WAVE AND LIGHT UNIT TEST Name________________________
Sample Test 2014. (see updated outline, here Wave Nature of Light)
1. An electromagnetic radiation has a wavelength of 250 nm. What is its frequency? (1)
2. Helium-neon laser light ( 638nm wavelength ) passes through a tiny crack onto a screen 1.5 m away. A diffraction pattern that is created has a 3.8 cm wide central maxima.
Determine the width of the crack. (3)
b) Determine the angle that is created between the first maxima (bright areas on either side of the central maxima)(2
3. Polarization demonstrates that light behaves like a _____________ wave.
4. diffraction grating has 800 slits/cm. When light with a wavelength of 770 nm is directed through the grating, what will be the separation of bright spots on a screen 3.7 m away?
5. Monochromatic light with a wavelength of 630 nm from a point source illuminates two parallel narrow slits. An interference pattern is formed on a screen 120 cm away. The distance between the first and seventh dark fringe is 3.4 mm. Determine the separation of the slits(3)
6. Briefly explain using a diagram, how Thomas Young’s experiment supported the wave model of light. (3)
7. Sofiya photographs the following interference pattern of a ripple tank with two sources that are vibrating in phase at 30 Hz. The scale of the photograph is 1.0 cm = 10.0 cm.(like clas practice question)
Using point ‘*’ and the given formulas, determine the wavelength of the waves. Show all work and construction lines. (7)
all the measurements (2)
a) PS - PS = n-1/2 (2)
b) sin = (n-1/2) /d (1)
c) = X d (1)
L (n-1/2)
d) What is the approximate speed of the waves? (1)
Answers.
1. 1.2 x 1015 Hz. 2. 5.03 x 10-5m b) 1.45 o 3. transverse 4.0.23m 5. 1.33x 10-6m
More practice
A diffraction grating has 800 slits/cm. When light with a wavelength of 770 nm is directed through the grating, what will be the separation of the bright spots on a screen 32.7 m away?
answer 2.01 m?
2. Helium-neon laser light (λ = 6.38 x10^-7) passes through a tiny crack onto a screen 1.5 m away. A diffraction pattern that is created has a 3.8 cm wide central maxima. Determine the width of the crack.
answer 5.05 x10^-5?
3. Light from a helium-neon later having a wavelength of 6.33 x10^-7 m is passed through a single slit which has a width of 8.6x10^-5m. The distance between the second minimum and the fifth order bright fringe is 7 cm. Find the distance between the slit and the screen.
Answer 2.7m
4. A 713- nm thick soap film
(nfilm=1.33) rests on a glass plate (nglass=1.52). White light strikes the film at normal incidence. What visible wavelengths will be constructively reflected from the film?
Answer 632 nm and 474 nm