Optics Answers

X-ray with energy 12 keV is used to measure Bragg-reflection peaks. The third-order peak is measured for the X-ray beam incident at an angle of 30 degrees with

respect to the horizontal. What is the spacing between the atomic planes? What

is the angle at which the first-order reflection peak is observed?

White light with wavelength range 450 - 900 nm is incident normally on a thin film

of refractive index 1.3. Light of wavelengths 500, 600, 750 nm is reflected back.

What is the minimum thickness of the film? If we could use light from 400 - 4000

nm, what other wavelengths will be reflected back?

A beam of light passes from water through a thin layer of oil and into air, as shown in the image below. If the incident angle in the water is 20° (the picture is not to scale), at what angle of refraction will the light beam pass from the oil to the air? Show your work and explain your reasoning. The index of refraction of water is 1.33 and the index of refraction of oil is 1.55.

Picture Link: https://ibb.co/JqGYLpj

A camera is equipped with a lens with a focal length of 39 cm. When an object 2.6 m (260 cm) away is being photographed, what is the magnification?

Question 25 (2 points)

The speed of light in a certain substance is only 92% of what it would be in a vacuum. What is the index of refraction of this substance?

Question 25 options:

A) 

3.1

B) 

4.1

C) 

No option is correct

D) 

1.1

E) 

2.1

Question 22 (2 points)

When light is refracted into a medium

Question 22 options:

A) 

its wavelength increases but frequency remains unchanged

B) 

its wavelength decreases but frequency remains unchanged

C) 

its wavelength and frequency both decrease

D) 

No option is correct

E) 

its wavelength and frequency both increases

Question 21 

An under-water swimmer cannot see very clearly even in absolutely clear water because of

Question 21 options:

A) 

Scattering of light in water

B) 

No option is correct

C) 

Reduction of speed of light in water

D) 

Change in the focal length of eye lens

E) 

Absorption of light in water

Question 13 (4 points)

A concave mirror has a radius of curvature of 40.5 cm and is positioned at a distance such that the upright image of a person's face is 1.5 times the size of his face. How far is the mirror from the person's face?

Question 13 options:

A) 

No option is correct

B) 

+4.75 cm

C) 

+ 5.75 cm

D) 

+3.75 cm

E) 

+ 6.75 cm

The sun is just covered by a disc of 2cm diameter placed about 2m from the eye. If the length of the diameter of the sun's image formed by a pin-hole camera is 0.5cm. Calculate the distance from the pin-hole to the screen

In Newton’s ring experiment the diameter of 16

th bright ring changes from 1.8 cm to 1.5cm when a liquid is

introduced the plate and the lens. Find the refractive index of the liquid and the diameter of the 5

th dark ring