Final Exam Questions

Question 1

Plane mirrors, convex mirrors and diverging lenses can never produce a

Answer 1

real image

Question 2

The Farther away the object is located, the ______ the image is and the closer the object is located on the focal plane, the image is ________

Answer 2

Smaller and Larger

Question 3

A converging lens can produce

Answer 3

real and virtual images

Question 4

A virtual image is formed when

Answer 4

the object is inside the focal length

Question 5

What characteristics do diverging lens have?

Answer 5

The lens concaves inwards much like a (

Question 6

How would you expect the focal length of a converging lens to change when it is immersed in water?

Answer 6

The focal length increases

Question 7

Objects in water are

Answer 7

further, than they appear

Question 8

A converging lens has a focal length of 7cm. If an object is placed at a distance of 17cm from the lens, then which of the following is true of the object’s image?

Answer 8

The image is real, inverted shrunk and located on the other side of the lens

Question 9

What is the critical angle for internal reflection given two mediums?

Answer 9

Use Snells Law

Divide the Mediums, lower medium first

Second Medium = 2.173

= Invert Sin Function to get answer

Question 10

Which of the following diagrams best represents the path followed by the light through the glass wall and into water

Answer 10

Calculate index of refraction and retrieve angle

Measure the images to find the closest corresponding angle that matches calculation.

Question 11

Which of the following describes the Fermat Principle and its applicaton to optical systems. Light always follows the path of

Answer 11

Shortest time between two points

Question 12

When light passes through a narrow opening, it is broadened due to diffraction. When the opening becomes more narrow, the diffraction pattern ____

Answer 12

becomes wider

The more narrow opening, the wider diffraction pattern.

Question 13

Dispersion does not cause ____

Answer 13

bending of light

Question 14

What is caused by dispersion?

Answer 14

Rainbows
Chromatic Aberration
Splitting of colors by a prism

Question 15

The larger the pupil, the____

Answer 15

more it can resolve detail at the same distance

Question 16

Objects in water always are always _____

Answer 16

further, than they appear.

Question 17

A real image forms _______

Answer 17

where light rays really do converge at a point. An example is a projector projecting an image onto a screen.

Question 18

A virtual image forms ____

Answer 18

A virtual image is said to exist at the point which light rays appear to diverge from even though they really dont. AN example is looking at yourself in the mirror. Flat mirrors produce virtual images and also converging,diverging lenses

Question 19

What do you do when given a prism and an index?

Answer 19

Calculate the critical angle of reflection using Snells law of index of refraction.

Obtain Critical Angle

Question 20

Total internal reflection occurs when ______?

Answer 20

Total internal reflection occurs when the reflection exceeds the critical angle.

Question 21

What happens when light does not exceed the critical angle?

Answer 21

It is replaced by refraction and it does not follow the same path.

Question 22

Why do slides needed to be placed upside down for old 35mm film slides back in the day?

Answer 22

The slider projector uses a converging lens which produces an inverted real image and therefore, flipping the slide upside down for an image that would be projected upside down would result in an image that appears “normal” to the human eye.

Question 23

The original Death star, featured in the movie Rogue One had a diameter of 160km. Near the end of the movie it is shown rising over the horizon of the planet Scarif, and seen from the surface it presents an apparent angular size of 20 degrees. How far away from the planets surface was the Death Star at that moment?

Answer 23

Use Tan*(20) = x

Divide Distance 160km
————
X

= Answer

Question 24

What changes occur to the wavelength when the temperature of the surface decreases?

Answer 24

With lower/warmer temperature, the wavelength of the peak increases and the area under the curve decreases.

Question 25

What changes occur to the wavelength when the emissivity of the surface increases?

Answer 25

With higher emissivity, the overall scale of the curve increases, but the peak stays the same.

Question 26

Why can we see a red glow from steel at a high temperature?

Answer 26

The red glow is caused by the low-intensity short-wavelength tail of the blackbody distribution. The tail extends long enough to just reach the visible spectrum at the temperature.

Question 27

What is a blackbody?

Answer 27

The spectrum of a blackbody is continuous (it gives off some light at all wavelengths), and it has a peak at a specific wavelength. The peak of the blackbody curve in a spectrum moves to shorter wavelengths for hotter objects.

Question 28

What is Weins Displacement Law?

Answer 28

Wien’s displacement law states that the black-body radiation curve for different temperature peaks at a wavelength is inversely proportional to the temperature.

Question 29

What is the photoelectric effect?

Answer 29

The photoelectric effect is the emission of electrons or other free carriers when light falls on a material. Electrons emitted in this manner can be called photoelectrons. This phenomenon is commonly studied in electronic physics, as well as in fields of chemistry, such as quantum chemistry or electrochemistry.

Question 30

On what part of your retina is the image of something being formed?

Answer 30

Images form on the fovea, the region of the retina with the highest density of photoreceptors.

Question 31

What happens when you try to keep an image in focus?

Answer 31

To keep the image in focus on the retina, the eye lens becomes progressively weaker (thinner), that is its optical power decreases.

Question 32

What is the focal length of the cornea that has a optical power of +40 dioptors.

Answer 32

Focal Length = 1
———
40

= 0.025m or 2.5cm

Question 33

What is used to correct Myopia(nearsightedness) in corrective surgery?

Answer 33

In myopia, distant objects are blurred because the lens cant weakens enough even when fully relaxed. So the cornea can be weakened instead so the eyes overall optic powerwill still be lowered.

Question 34

Explain what it means to have 20/50 vision etc..

Answer 34

It means at a distance of 20ft, it can distinguish details that are normally distinguishable at 50ft.

Question 35

Describe what differentiates the fovea from the rest of the retina in terms of structure and function

Answer 35

The fovea contains the greatest density of photoreceptors but theyre all cone cells - no rods are found there

whereas the rest of the retina features mostly rod cells .

The fovea is responsible for high acuity (resolution) when looking directly at an object.

Question 36

Explain what presbyopia is.

Answer 36

Presbyopia is the result of aging of the lens such that it cant strengthen enough to form in-focus images of close-by objects. A converging lens moves the image of an object further away, allowing the lens to focus it without need for so much strength.

Question 37

What are photoreceptors?

Answer 37

There are two types of photoreceptors in the human retina, rods and cones.

Rods are responsible for vision at low light levels (scotopic vision). They do not mediate color vision, and have a low spatial acuity.

Cones are active at higher light levels (photopic vision), are capable of color vision and are responsible for high spatial acuity.