PHYSICS HOMEWORK XI-FOR FRIDAY 16TH DEC

SET 1

1.      A horizontal circular turntable rotates about its center at the uniform rate of 120 rev/min. Find the greatest distance from the center at which a small body will remain stationary relative to the turn table, if the coefficient of static friction between the turntable and the boy is 0.8.
2.      A ball of mass 100 g is suspended by a string of length 40 cm. Keeping the string always taut, the ball describes a horizontal circle of radius 10 cm. Find the angular speed of the ball.
3.      ABCD is the plane of a glass tube. A horizontal beam of light entering the face AB at glancing incidence. Show that the angle θ which any ray emerging from BC would make with the normal to BC is given by sinθ=cotα, where α is the critical angle.
4.      A 200 kg satellite is lifted to an orbit of 2.2×10⁴ km radius. If the radius and mass of the earth are 6.37×10⁶ m and 5.98×10²⁴ kg respectively, how much additional potential energy is required to lift the satellite?
5.      Find the rms speed of nitrogen at NTP. Density of nitrogen= 1.29 kg/m³ at NTP.
6.      The silica cylinder of a radiant wall heater is 0.6 m long and has a radius of 6 mm. If it is rated at 1.5 Kw, estimate it’s temperature when operating.
7.      What is a black body? How it is realized in practice?
8.      A luminous object and a screen are mounted on an optical bench and a converging lens is placed between them so that a sharp image is formed on the screen. The linear magnification of the image is found to be 2.5. The lens is now moved 30 cm nearer the screen and a sharp image is again formed. Find the focal length of the lens.
9.      Two thin lenses of focal length 10 cm and 20 cm are placed in contact. Calculate the effective power of the combination.

SET 2
10.  The image obtained with a converging lens is erect and three times the length of the object. The focal length of the lens is 20 cm. calculate the object and image distances.
11.  Why are roads banked on curved path?
12.  What is the source of centripetal force to a satellite revolving round the earth?
13.  The positively charged nucleus of an atom attracts the electron in the orbits. Why do the electrons not collapse into the nucleus?
14.  The weight of the body is less in mine. Is it true? Explain.
15.  What do you mean by weightlessness?
16.  Would you have more sugar of 1 kg at the poles or at the equator?
17.  Calculate the period of revolution of a satellite revolving at a distance of 20 km above the surface of the earth. Radius of earth= 6400 km.
18.  How can water be boiled in a paper cup?


SET 3
19.  A ray of light falls normally on a refracting face of a prism of refractive index 1.5. Find the angle of prism if the rays just fail to emerge from the other refracting surface.
20.  For a yellow light, the refractive index for the material of the prism is √2 and the angle of prism is 60⁰. Calculate the angle of minimum deviation.
21.  A narrow beam of light is incident normally on one face of an equilateral prism (refractive index 1.45) and finally emerges from the prism. The prism is now surrounded by water (refractive index 1.33). What is the angle between the directions of the emergent beam in two cases?
22.  A certain prism is found to produce a minimum deviation of 51⁰, while it produces a deviation of 62⁰ 48’ for two values of the angle of incidence namely 40⁰ 6’ and 82⁰ 42’ respectively. Determine the refracting angle of the prism, the angle of incidence at minimum deviation and the refractive index of the material of the prism.
23.  Which of blue and red light will be deviated more by a prism and why?
24.  On what factors the deviation produced by a prism depend?
25.  What is the condition for minimum deviation when a ray passes through a prism?
26.  What is grazing incidence and grazing emergence?

SET 4
27.  Does the angle of deviation of a small angled prism depend on angle of incidence?
28.  What is the apparent position of an object below a rectangular block of glass 6 cm thick if a layer of water 4 cm thick is on the top of the glass?
29.  A ray of light is incident at an angle of 60° on one of a glass plate 4 cm thick. Find the lateral displacement between the incident ray and the emergent ray.
30.  Light from a luminous point on the lower face of a rectangular glass slab 2 cm thick, strikes the upper face and the totally reflected rays outline a circle of 3.2 cm radius on the lower face. What is the refractive index of the glass?
31.  Under what condition does a concave lens form a real image?
32.  Sun glasses have curved surfaces. But their power is zero. Why?
33.  What is power of a lens? Write its unit.
34.  Does the focal length of a thin lens increase, decrease or remains the same if monochromatic red light is used instead of blue light to measure it?
35.  An air bubble is formed inside water. Does it act as a converging lens or a diverging lens?
36.  Why have concave lens two focal points and a mirror only one?

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