Question

1.) Two slits have a separation, 4.15*10^-2 m. An interference pattern is created 5.25 m away from the slits, with a distance 0.324 m between the central bright fringe and the 8th dark fringe below it. What is the wavelength of light used to create the pattern? A.)3.14*10^-4 B.) 1.28*10^-3 C.) 4.80*10^-4 D.) 0.308

2.) What is the diameter of an aperture needed for two objects to be viewed as separate, if the minimum angle is 5.79 degrees (0.101 radians) and the wavelength of light is 508 nm? A.) 3.16*10^4 B.) 1.58*10^4 C.) 6140 D.) 107

3.) A light, with wavelength, 374 nm in air, is sent towards to mediums, A and B. Both A and B are not air. If the light first travels in B, total internal reflection can happen at some angles when it hits the interface between B and A. Now if the light first travels in A towards B and gets reflected by B, which of the statements below is true about the lighted reflected by B? A.) Phase shift of 187 nm takes place after reflection B.) no phase shift C.) Polarized light is generated D.) None are correct

Answer 1

1)

In case of constructive interference, we have the relation for the distance between the two fringes

y = n D / d

where D is the distance to the screen, d is slit separation

so,

= yd / nD

= 0.324 * 4.15e-2 / 8 * 5.25

= 3.14e-4 m

___________________

2)

= 1.22 / D

0.101 = 1.22 * 508e-9 / D

solve for D,

D = 6.136e-6 m

option (C) - 6140 is fine ( you forgot to mention the units !!)