Exam 25: Optical Instruments

A very delicate sample is placed 0.150 cm from the objective lens of a microscope. The focal length of the objective is 0.140 cm, and that of the eyepiece is 1.0 cm. The near-point distance of the Person using the microscope is 25.0 cm. The magnitude of the final magnification of the Microscope is closes to

The length of a telescope is 2.00 m and the focal length of the objective lens is 2.0 cm. What is the focal length of the eyepiece?

A student wishing to build a telescope has available an eyepiece of focal length -5.0 cm. What focal length objective is needed to obtain a magnification of 10?

A camera used for aerial mapping has a lens with a 30-cm diameter maximum aperture and a 42-cm focal length. Light of 550 nm wavelength is used to form the image. Assuming that the Resolution of the camera is limited only by diffraction, what is the smallest angle (in milliradians) Subtended by an object on the ground that can be resolved by this camera at maximum aperture?

A nearsighted person cannot see objects beyond 80 cm from his eyes. Which one of the following combinations represents the correct focal length and the refractive power of the contact lenses that Will enable him to comfortably see the distant objects clearly?

A simple refracting telescope provides large magnification by employing

A telescope has an angular magnification of 250 when used with a 20 mm eyepiece. What is the focal length of the objective lens?

What type of lens is used to make a magnifying glass?

A zoom lens for a camera is adjusted to change its focal length from 38 mm to 304 mm. If the same amount of light is to be admitted to the lens in both cases, what is the final f-number if the original f-number was f/2.0?

The focal lengths of the objective lens and the eyepiece of a microscope are 0.50 cm and 2.0 cm, respectively, and their separation adjusted for minimum eyestrain is 6.0 cm. If the microscope is Focused on a small object, what is the distance between the object and the objective lens?

A researcher is using $x$ -rays to investigating a cubic crystal. He is looking at Bragg reflection from the planes parallel to the cube faces. He finds that when using $x$ -rays with a wavelength of $0.165 \mathrm {~nm}$ , a strong first maximum occurs when the beam makes an angle of $23.5 ^ { \circ }$ with the planes. What is the spacing of adjacent atoms in this crystal?

What is the focal length of the corrective contact lens needed by a nearsighted person whose far point is at 60 cm?

A person with a near point at 25 cm uses a magnifying glass of focal length 10 cm. What is the maximum angular magnification possible with this glass?

A lens of focal length 40 mm is used as a magnifier. The object being viewed is 5.3 mm long, and is positioned at the focal point of the lens. The user of the magnifier has a near point at 25 cm. What Is the angular magnification of the magnifier?

The objective and the eyepiece of a refracting astronomical telescope have focal lengths of $320 \mathrm {~cm}$ and $4.0 \mathrm {~cm}$ , respectively. The telescope is used to view Neptune and the final image is set at infinity. The diameter of Neptune is $4.96 \times 10 ^ { 7 } \mathrm {~m}$ , and its distance from Earth at the time of observation is $4.4 \times 10 ^ { 12 } \mathrm {~m}$ . What is the angle (in milliradians) subtended by the final telescopic image of Neptune?

A student constructs an astronomical telescope and wishes it to have a magnification of 10. If the telescope has an objective lens of focal length 0.50 m, what must be the focal length of the Eyepiece?

A compound microscope has a 18-cm-long barrel and an objective lens with a focal length of 8.0 mm. What is the focal length of the eyepiece to give a total magnification of 240? It is adjusted for Minimum eyestrain for persons with a near point of 25 cm.

You have a choice between two lenses of focal lengths fa and fb, where fb = 2fa, to use as the objective lens in building a refracting telescope. If the magnification you obtain using lens a is Ma, What will be the magnification when using lens b?

An astronomical refracting telescope is made from two lenses. The objective lens has a focal length of 114 cm, and the eyepiece lens has a focal length of 17.0 cm. (a) What is the total length of the telescope? (b) What is the angular magnification of the telescope? (c) What is the magnification by turning the telescope around and looking through the objective Lens first?

Consider a magnifying glass with a power of $3.0$ diopters. (a) What is the maximum angular magnification for a person with a near point at $25 \mathrm {~cm}$ ? (b) What is the angular magnification when viewing with a relaxed eye?