Chapter 29, The Nature of Light Video Solutions, Introduction to biological physics for the health and life sciences

Problem 1

A diagnostic device uses a bright red laser light to illuminate structures just under the surface of the skin. Light from the laser passes first through the air, and then the skin, to scatter off the subcutaneous structures that are to be imaged. The scattered light passes back through the skin and into an optical device which forms an image of the scattered light on a CCD array. The laser light used has a wavelength of $633.0 \mathrm{~nm}$ in a vacuum. The refractive indices of air, the glass used in the imaging optics, and skin are $1.008,1.700$, and 1.381 respectively (use $c=2.998 \times 10^8 \mathrm{~m} \mathrm{~s}^{-1}$ for this question).
(a) What is the frequency of the red light when it passes through each material?
(b) What is the wavelength of the red light as it passes through each material?
(c) How fast does the red light travel through each material?

Mayukh Banik

Numerade Educator

00:44

Problem 2

It is not possible to make images of, and therefore see, arbitrarily small objects using visible light. The minimum size of an object that can be 'seen' by light using conventional optics is roughly equal to a few times the wavelength of the light used. If a bacterium that is $1.2 \mu \mathrm{m}$ across can just be seen using a particular optical system when the bacteria is floating in a watery solution ( $n_{\text {solution }}=1.35$ ), what will be the minimum size of bacterium that this optical system could 'see' in air $\left(n_{\text {air }}=1.0\right)$ ?

Sean Dougherty

Numerade Educator

01:38

Problem 3

Light strikes a mirror as shown in Figure 29.12. This mirror has another mirror placed at right angles to it. Such an arrangement of mirrors is known as a comer reflector. At what angle does the light get reflected back (i.e., what angle is the outgoing light at when it crosses the dotted line)?

Figure 29.12 Two mirrors are placed a right angles to one and other. This arrangement of minors reflects light in a partioular fashion, making them useful for a range of purposes.

Pankaj Jain

Numerade Educator

06:38

Problem 4

The glass half-cylinder prism shown in Figure 29.13 is used to measure the critical angle for light of various wavelengths. For red Ilght the critical angle measured was $36.78^{\circ}$. For blue light the critical angle was $36.28^{\circ}$ (The refractive index of air is $n=1.0$ ).
(a) What is the refractive index of the glass for red light?
(b) What is the refractive index of the glass for blue light?

Shoukat Ali

Other Schools

09:15

Problem 5

A beam of white light passes through a $1.5 \mathrm{~cm}$ thick pane of glass at an angle of $45^{\circ}$ as shown in Figure 29.15. The refractive index of the glass for light of wavelength $470 \mathrm{~nm}$ (deep blue) is 1.66 while the refractive index of the glass for light of wavelength $630 \mathrm{~nm}$ (bright red) is 1.60 .
(a) What is the spacing, $S$, between the red and blue components of a narrow beam after they have passed through the pane of glass?
(b) Use your answer in (a) to explain why we do we not ordinarily see the effects of dispersion when looking through flat panes of glass.
(c) How thick would the pane of glass need to be for the separation of the red and blue rays to be $1 \mathrm{~cm}$ ?

Khoobchandra Agrawal

Numerade Educator

09:03

Problem 6

A beam of light of wavelength $550 \mathrm{~nm}$ strikes a water droplet as show in Figure 29.14. What are the angles $\theta_{\mathrm{A}}$ and $\theta_{\mathrm{B}}$ at which the reflected and refracied beams travel?
Figure 29.14 A beam of light hits a spherical water droplet.

Sheh Lit Chang

University of Washington

03:12

Problem 7

A fish in a pond looks up and sees the light from a street lamp at an angle of $35^{\circ}$ to the vertical. If the street light is $5.5 \mathrm{~m}$ tall and the fish is $30 \mathrm{~cm}$ below the surface of the pond and $3 \mathrm{~m}$ from its edge, how far from the edge of the pond is the street lamp? ( $n_{\mathrm{air}}=1$, and $n_{\text {wates }}=1.33$ )

Shoukat Ali

Other Schools

03:52

Problem 8

Two divers jump out of their boat and swim straight down to a depth of $10 \mathrm{~m}$. The water surface becomes calm again very quickly after the divers jump in. Once the divers reach their final depth they begin to swim in opposite directions at the same rate while periodically stopping to shine a flashlight back at the surface of the water where they had jumped in. After the divers have swum far enough apart they begin to notice a strong reflection from the other diver's flashlight that was not present before. How far apart are divers when this starts to happen? $\left(\mu_{\text {air }}=1.0\right.$, and $n_{\text {water }}=1.33$ )

Mayukh Banik

Numerade Educator

04:15

Problem 9

By what angle (Ocomea) is the beam of light shown in Figure 29.16 deviated as it passes from air to the comea if the incident angle is $\theta_i=23.6^{\prime}$ ? The refractive index of air is $n_{a i r}=1.00$, the refractive index of the comea is $n_{\text {comea }}=1.38$. Ignore further deviation of light as it passes from the cornea into the aqueous humour, etc.

Figure $\mathbf{2 9 . 1 6}$ Moat of the bending of light in te eye is done at the air-comea irfortaco. The lens is reaponsible for only a small amount of the bercing, but of course is acfustable.

Julie Farhm

Numerade Educator

04:26

Problem 10

The ability of your eyes to focus is impaired when you attempt to look around underwater (if you are not wearing a pair of swimming goggles). Recalculate your answer for Problem 29.9 for the case in which the eye is submerged in water ( $n_{\text {water }}=1.33$ ).

Khoobchandra Agrawal

Numerade Educator