A compound microscope has a total magnification $|m|=500$, using an eyepiece whose magnification is $20$. What is the focal length of the objective lens?

Small binoculars or opera glasses are useful in seeing the stage in detail. No prisms or mirrors are used, and yet the magnified image in these glasses is not inverted. Are the eyepieces converging lenses or diverging lenses?

You have two unlabeled laser discs, one a CD and the other a DVD. Describe how you might use a laser pointer to tell which is which.

A compound microscope has an objective lens that by itself produces a magnification of $-15$. The total magnification of the microscope is designed to be $-150$.

(a) What is the focal length of the eyepiece?

(b) Why is the value of the magnification negative?

The distance between the objective lens and the eyepiece of a microscope is $30 \mathrm{~cm}$. If the eyepiece has a magnification of $20$ and the total magnification of the microscope is $|m|=250$, what is the focal length of the objective lens?

You are asked to design an optical fiber. Should the refractive index of the core material be larger or smaller than that of the surrounding cladding? For the fastest transmission times, do you want a high or a low refractive index for the core material?

A compound microscope in which the objective and eyepiece are $20 \mathrm{~cm}$ apart uses an objective lens with $f_{\mathrm{obj}}=1.0 \mathrm{~cm}$ and an eyepiece with $f_{\text {eyepicce }}=5.0 \mathrm{~cm}$. How would the magnification change if the focal length of the objective lens were decreased by a factor of three?

DVD players use a laser with a higher frequency than that of CD players. Why can DVD players read CDs, but CD players cannot read DVDs?

A compound microscope in which the objective and eyepiece are $20 \mathrm{~cm}$ apart uses an objective lens with $f_{\mathrm{obj}}=1.0 \mathrm{~cm}$ and an eyepiece with $f_{\text {eyepicce }}=5.0 \mathrm{~cm}$. What is the magnification of the microscope?

A photographer intends to take a photograph of a country landscape with a large depth of field such that the flowers in the foreground of the picture and a barn in the distance are both in sharp focus. What conditions are more suitable to such a photo, a bright and sunny day or a dim and overcast day? Explain your choice.

Suppose you have a near-point distance of $25 \mathrm{~cm}$. The angular resolution of the eye is determined by diffraction and the Rayleigh criterion and is approximatcly 1 arcmin $=1^{\prime}$. With a near-point distance of $25 \mathrm{~cm}$, what is the smallest object a person can resolve using a magnifying glass with a magnification of $10$ ?

Does a camera use a diverging lens or a converging lens? Does a Figure camera produce a real image or a virtual image?

Suppose you have a near-point distance of $25 \mathrm{~cm}$. The angular resolution of the eye is determined by diffraction and the Rayleigh criterion and is approximatcly $1$ arcmin $=1^{\prime}$. What is the smallest object your eye can resolve without a magnifying glass?

Your friend is farsighted with a near-point distance of $500 \mathrm{~cm}$. What should the focal length be for the lenses in his reading glasses? Assume the glasses are placed $2.0 \mathrm{~cm}$ in front of his eyes.