# College Physics

Physics & Astronomy

## Quiz 11 :Optical Instruments

Showing 1 - 20 of 77
A lens is used to examine an object across a room. Is the lens probably being used as a simple magnifier Explain in terms of focal length, the image, and magnification.
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The magnification of a magnifier depends upon the near point of the person and the focal length of the lens. A magnifier forms an enlarged, upright and virtual image of an object at or inside the focal point of the lens. A lens with short focal length can be used to get high magnifications and so an enlarged virtual image.
Here the person will be observing the object across a room with the object being at large distances and the image being observed at a small distance from the lens. So the magnitude of the magnification of the lens would be less than one. Hence, the person will not be using the lens as a magnifier.

A lens has a focal length of 28 cm and a diameter of 4.0 cm. What is the f -number of the lens
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Use the relation between focal length, diameter, and f - number of the lens to solve for the
f - number of the lens.
The expression which relates focal length, diameter, and f - number of the lens is, Here, f is the focal length of the lens, and D  is the diameter of the lens.
Substitute 28 cm for f , and 4.0 cm for D in the equation to solve for . Therefore, the f - number of the lens is .

A laser beam is incident at a shallow angle on a horizontal machinist's ruler that has a finely calibrated scale. The engraved rulings on the scale give rise to a diffraction pattern on a vertical screen. Discuss how you can use this technique to obtain a measure of the wavelength of the laser light.
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A laser beam is incident at a shallow angle on a horizontal machinist's ruler that has a finely calibrated scale and this engraved rulings on the scale give rise to a diffraction pattern on a vertical screen as shown in the below figure.
Figure (a) shows the diffraction pattern produced by a laser light incident on scale. Figure (a)
Light from the laser beam is nearly parallel to the horizontal ruler will scatter from ruler marks, which are separated by a distance apart to produce a diffraction pattern on a vertical wall at a distance away.
The condition for constructive interference is, Here, The figure (a) includes two triangles. Redraw the first triangle as shown below. From above figure, the sin angle is, From the second triangle, the tan angle is, For a small angle .
Then above equation changes as, Substitute for and for in equation . Substitute for in equation and solve for . Since and are measurable, the wavelength of the laser beam can be calculated by measuring the height of the bright spots as .

A certain camera has f -numbers that range from 1.2 to 22. If the focal length of the lens is 55 mm, what is the range of aperture diameters for the camera
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The optic nerve and the brain invert the image formed on the retina. Why don't we see everything upside down
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A photographic image of a building is 0.092 0 m high. The image was made with a lens with a focal length of 52.0 mm. If the lens was 100 m from the building when the photograph was made, determine the height of the building.
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Suppose you are observing the interference pattern formed by a Michelson interferometer in a laboratory and a joking colleague holds a lit match in the light path of one arm of the interferometer. Will this match have an effect on the interference pattern
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The image area of a typical 35 mm slide is 23.5 mm by 35.0 mm. If a camera's lens has a focal length of 55.0 mm and forms an image of the constellation Orion, which is 20° across, will the full image fit on a 35-mm slide
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If you want to examine the fine detail of an object with a magnifying glass with a power of 120.0 diopters, where should the object be placed so as to observe a magnified image of the object
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A camera is being used with a correct exposure at f /4 and a shutter speed of s. In addition to the f -numbers listed in Section 25.1, this camera has f -numbers f /1, f /1.4, and f /2. To photograph a rapidly moving subject, the shutter speed is changed to s. Find the new f -number setting needed on this camera to maintain satisfactory exposure.
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Compare and contrast the eye and a camera. What parts of the camera correspond to the iris, the retina, and the cornea of the eye
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(a) Use conceptual arguments to show that the intensity of light (energy per unit area per unit time) reaching the film in a camera is proportional to the square of the reciprocal of the f -number as (b) The correct exposure time for a camera set to f /1.8 is (1/500) s. Calculate the correct exposure time if the f -number is changed to f /4 under the same lighting conditions. Note: " f /4," on a camera, means "an f - number of 4."
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If you want to use a converging lens to set fire to a piece of paper, why should the light source be farther from the lens than its focal point
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A certain type of film requires an exposure time of 0.010 s with an f /11 lens setting. Another type of film requires twice the light energy to produce the same level of exposure. What f -number does the second type of film need with the 0.010-s exposure time
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Large telescopes are usually reflecting rather than refracting. List some reasons for this choice.
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A certain camera lens has a focal length of 175 mm. Its position can be adjusted to produce images when the lens is between 180 mm and 210 mm from the plane of the film. Over what range of object distances is the lens useful
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