Exam 25: Optical Instruments

The objective lens and the eyepiece of a microscope have focal lengths of 4.0 mm and 25 mm, respectively. The objective produces a real image 30 times the size of the object, with the final Image viewed at infinity. The near point of the microscope user is at 25 cm. What is the distance Between the objective lens and the real image that it produces?

A round 0.85-mm-diameter hole is illuminated by infrared light of wavelength 2.5 µm What is the angle of the first dark fringe in the resulting pattern?

If a camera lens lets in an amount of light $I$ when it is set to $f / 4$ , then how much light will it let in when it is set to $f / 8$ ?

Certain planes of a crystal of halite have a spacing of $0.399 \mathrm {~nm}$ . The crystal is irradiated by a beam of $x$ -rays. First order constructive interference occurs when the beam makes an angle of $20 ^ { \circ }$ with the planes of the crystal surface. What is the wavelength of the $x$ -rays?

A person having a near point of 25 cm uses a magnifying glass with a focal length of 10 cm. What is the angular magnification of the glass for that person when her eyes are focused at infinity?

A myopic (nearsighted) child wears contact lenses that allow her to have clear distant vision. The power of the lenses of her eyeglasses is -3.00 diopters. Without the corrective lenses, what is the far Point of the girl?

What power contact lens must be used to correct the vision of a nearsighted person whose far point is 40 cm?

A camera lens has a focal length of 50.0 mm and an aperture setting of f/4.00. What is the diameter of the aperture of this lens?

A farsighted girl has a near point at 2.0 m but has forgotten her glasses at home. The girl borrows eyeglasses that have a power of +2.75 diopters. With these eyeglasses, what is the near point of the Girl, assuming that she wears them extremely close to her eyes?

A nearsighted person wears contact lenses having a power of -0.15 diopters. What is the person's uncorrected far point?

You have available lenses of focal lengths 2.0 cm, 4.0 cm, 8.0 cm, and 16.0 cm. If you could use any two of these lenses to build a telescope, what is the maximum magnification you could achieve for Comfortable viewing of a planet?

You are given two converging lenses to build a compound microscope. Lens A has focal length 0.50 cm and lens B has focal length of 3.0 cm. Which one of the two lenses would you use for the Objective?

What is the limiting angle of resolution for a lens of radius 2.0 mm when viewing with light having a wavelength of 600 nm?

What is the focal length of a contact lens that will allow a person with a near point of 125 cm to read a physics book held 25.0 cm from his eyes?

The length of the telescope is 1.60 m, and it has a magnification of 60.0. What is the focal length of the objective lens?

What is the angular magnification of a magnifying glass of focal length 4.0 cm if the image is to be viewed by a relaxed eye having a near point of 25 cm?

A microscope has an objective lens of focal length 1.40 mm and an eyepiece of focal length 20.00 mm. It is adjusted for minimum eyestrain for persons with a near point of 25.0 cm. A blood Sample is placed 1.50 mm from the objective. How far apart are the lenses?

The focal length of the objective lens of a telescope is 75.0 cm, and the eyepiece has a focal length of 6.00 cm. What is the magnification of this telescope?

Certain planes of a crystal of halite have a spacing of $0.399 \mathrm {~nm}$ . The crystal is irradiated by a beam of x-rays. First order constructive interference occurs when the beam makes an angle of $20 ^ { \circ }$ with the planes of the crystal surface. What angle does the beam make with the crystal planes for second order constructive?

The angular magnification of a magnifying glass is largest when the image is at