Q: Which formula correctly expresses the resolving power of a microscope?

$$\text{Resolving power} = \frac{\text{wavelength of light}}{2 \times \text{numerical aperture}}$$

Q: If a microscope has a numerical aperture of 1.25 and uses light with a wavelength of 500 nm, what is its theoretical resolving power?

$$\text{Resolving power} = \frac{500}{2 \times 1.25} = 200 \text{ nm}$$

Question 1

Which of the following best describes the relationship between focal length and magnification in a microscope lens?

Accepted Answer

Shorter focal length results in higher magnification.

Question 2

A microbiologist is using a compound microscope and wants to observe bacteria that are 0.2 μm apart. Which property of the microscope is most critical for this observation?

Accepted Answer

Resolution (resolving power)

Question 3

Which formula correctly expresses the resolving power of a microscope?

Accepted Answer

$$	ext{Resolving power} = \frac{	ext{wavelength of light}}{2 	imes 	ext{numerical aperture}}$$

Question 4

Why is immersion oil used with high-magnification objective lenses in light microscopy?

Accepted Answer

It matches the refractive index of glass, reducing light bending and loss.

Question 5

Which of the following units is the smallest?

Accepted Answer

Nanometer (nm)

Question 6

A student observes that the image under the microscope is blurry and cannot distinguish two points that are 0.15 μm apart. What is the most likely explanation?

Accepted Answer

The wavelength of light used is too long to resolve such small distances.

Question 7

Which of the following best defines numerical aperture in microscopy?

Accepted Answer

A function of the diameter of the objective lens in relation to its focal length, indicating the lens's ability to gather light and resolve detail.

Question 8

If a microscope has a numerical aperture of 1.25 and uses light with a wavelength of 500 nm, what is its theoretical resolving power?

Accepted Answer

$$	ext{Resolving power} = \frac{500}{2 	imes 1.25} = 200 	ext{ nm}$$

Question 9

Which scenario best illustrates the concept of refraction as it applies to microscopy?

Accepted Answer

A light ray bends as it passes from air into immersion oil, reducing loss of light.

Question 10

A researcher wants to distinguish two bacteria that are 0.1 μm apart. Which adjustment would most improve the microscope's ability to resolve these bacteria?

Accepted Answer

Use a shorter wavelength of light.

Question 11

Which of the following is true regarding the difference between a micrometer and a nanometer?

Accepted Answer

A micrometer is $$10^{-6}$$ meters, while a nanometer is $$10^{-9}$$ meters.

Question 12

Why can't white light resolve structures less than 0.18 μm apart in a light microscope?

Accepted Answer

White light has a long wavelength, limiting resolution.

Question 13

Which of the following best explains why oil immersion increases the resolving power of a microscope?

Accepted Answer

It increases the numerical aperture by reducing refraction.

Question 14

A student calculates the resolving power of a microscope using a wavelength of 400 nm and a numerical aperture of 1.0. What is the resolving power?

Accepted Answer

$$	ext{Resolving power} = \frac{400}{2 	imes 1.0} = 200 	ext{ nm}$$

Question 15

Which of the following is NOT a correct metric conversion?

Accepted Answer

1 centimeter (cm) = $$10^{-1}$$ meters (m)

Question 16

Which of the following best describes the function of the focal point in a microscope lens?

Accepted Answer

It is the point where light rays converge after passing through the lens.

Observing Microorganisms Through a Microscope: Units, Lenses, and Resolution

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