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Explain with the help of a ray diagram, the working of an astronomical telescope. The magnifying power of a telescope in its normal adjustment is 20. If the length of the telescope is 105 cm in this adjustment, find the focal lengths of the two

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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(i) Draw a labelled ray diagram showing the image formation of a distant object by refracting telescope. Deduce the expression for its magnifying power when the final image is formed at infinity. (ii) The sum of focal lengths of the two lenses of a refracting telescope is 105 cm. The focal length of one lens is 20 times that of the other. Determine the total magnification of the telescope when the final image is formed at

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Define magnifying power of a telescope. Write its expression. A small telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If this telescope is used to view a 100 m high tower 3 km away, find the height of the final image when it is formed 25 cm away from the

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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How is the working of a telescope different from that of a microscope? The focal lengths of the objective and eyepiece of a microscope are 1.25 cm and 5 cm, respectively. Find the position of the object relative to the objective in order to obtain an angular magnification of 30 in normal

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Draw a ray diagram to show the working of a compound microscope. Deduce an expression for the total magnification when the final image is formed at the near point. In a compound microscope, an object is placed at a distance of 1.5 cm from the objective of focal length 1.25 cm. If the eyepiece has a focal length of 5 cm and the final image is formed at the near point. Estimate the magnifying power of the

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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(i) (a) Draw a labelled ray diagram to show the formation of image in an astronomical telescope for a distant object. (b) Write the three distinct advantages of a reflecting type telescope over a refracting type telescope, (ii) A convex lens of focal length 10 cm is placed coaxially 5 cm away from a concave lens of focal length 10 cm. If an object is placed 30 cm in front of the convex lens. Find the position of the final image formed by the combined

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Draw the labelled ray diagram for the formation of image by an astronomical telescope. Derive the expression for its magnifying power in normal adjustment. Write two basic features which can distinguish between a telescope and a Compound

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A ray of light incident at an angle θ on a refracting face of a prism emerges from the other face normally. If the angle of the prism is 5° and the prism is made of a material of refractive index 1.5, the angle of incidence

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A short pulse of white light is incident from air to a glass slab at normal incidence. After travelling through the slab, the first colour to emerge

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An object approaches a convergent lens from the left of the lens with a uniform speed 5 m/s and stops at the focus. The

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A passenger in an aeroplane

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You are given four sources of light each one providing a light of a single colour – red, blue, green and yellow. Suppose the angle of refraction for a beam of yellow light corresponding to a particular angle of incidence at the interface of two media is 90°. Which of the following statements is correct if the source of yellow light is replaced with that of other lights without changing the angle of

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The radius of curvature of the curved surface of a plano-convex lens is 20 cm. If the refractive index of the material of the lens be 1.5, it

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The phenomena involved in the reflection of radiowaves by ionosphere is similar

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The direction of ray of light incident on a concave mirror is shown by PQ while directions in which the ray would travel after reflection is shown by four rays marked 1, 2, 3 and 4 (Fig ). Which of the four rays correctly shows the direction of reflected

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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The optical density of turpentine is higher than that of water while its mass density is lower. Fig . shows a layer of turpentine floating over water in a container. For which one of the four rays incident on turpentine in Fig . the path shown is

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A car is moving with at a constant speed of 60 km h–1 on a straight road. Looking at the rear view mirror, the driver finds that the car following him is at a distance of 100 m and is approaching with a speed of 5 km h –1. In order to keep track of the car in the rear, the driver begins to glance alternatively at the rear and side mirror of his car after every 2 s till the other car overtakes. If the two cars were maintaining their speeds, which of the following statement (s) is/are

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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There are certain material developed in laboratories which have a negative refractive index (Fig). A ray incident from air (medium 1) into such a medium (medium 2) shall follow a path given

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Consider an extended object immersed in water contained in a plane trough. When seen from close to the edge of the trough the object looks distorted

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A rectangular block of glass ABCD has a refractive index 1.6. A pin is placed midway on the face AB (Fig). When observed from the face AD, the pin

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