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Shubhrajyoti Ghosh
Subject: Physics
, asked on 15/3/18
Q. Two spherical mirrors - one convex and the other concave, are each of the same radius r. They are arranged coaxially at a distance 2r from each other. A small circle of radius a is drawn on the convex mirror near the pole. Prove that the radii of the first two images are a/3 and a/ 11.
Answer
1
Shubhrajyoti Ghosh
Subject: Physics
, asked on 15/3/18
No links please
Q. What do you mean by polarisation of light.
Compare between interference and diffraction. Establish Brewster's law.
Answer
1
Shubhrajyoti Ghosh
Subject: Physics
, asked on 15/3/18
No links please:
Q. A compound microscope consists of two lenses of focal lengths 0.8 cm and 3 cm respectively. If the object is 0.85 cm from the objective and the final image is to be 24 cm from the eye-piece, compute the magnifying power of the microscope.
A shot sighted person cannot see distinctly objects beyond 2m from the eye. Find the focal length and the powe rof the spectacle lens which will enable him to see distant objects clearly.
Answer
1
Shubhrajyoti Ghosh
Subject: Physics
, asked on 15/3/18
No links please
(b)
An object is D cm from a screen. A convex lens forms an image of it on the screen. When moved through a distance x cm, it forms another image. Prove that the ratio of the sizes of the two images produced is
${\left(\frac{D+X}{D-X}\right)}^{2}.$
Answer
2
Shubhrajyoti Ghosh
Subject: Physics
, asked on 15/3/18
No links please
Q. State Huygen's principle. In the light of Huygen's principle, explain the refraction of light.
Answer
1
Shubhrajyoti Ghosh
Subject: Physics
, asked on 15/3/18
No links please
Q.(b) A man can read a newspaper clearly which is placed at a distance 25 cm from the eye with the help of a spectacle of power + 3D. If he wants to read it without spectacle then how far he has to place the newspaper from his eye?
Answer
2
Shubhrajyoti Ghosh
Subject: Physics
, asked on 14/3/18
(c)
In an aquarium, a fish 6 cm long is swimming directly towards the plane glass front. If, at a certain moment, head of the fish is 18 cm behind the glass front, find the apparent length of the fish as seen by a person looking through the glass. Given R.I. of water =4/3.
Answer
1
Shubhrajyoti Ghosh
Subject: Physics
, asked on 14/3/18
No links please:
(b) The focal length of a glass lens in air is 5 cm. What will be its focal length in water ?
$\left\{{\mu}_{g}=1.51,{\mu}_{w}=1.33\right\}$
Answer
2
Shubhrajyoti Ghosh
Subject: Physics
, asked on 14/3/18
(b) An object is D cm from a screen. A convex lens forms an image of it on the screen. When moved through a distance x cm, it forms another image. Prove that the ratio of the sizes of the two images produced is
${\left(\frac{D+x}{D-x}\right)}^{2}$
[2 + 3]
Answer
1
Shubhrajyoti Ghosh
Subject: Physics
, asked on 14/3/18
No links please
Q. Find the focal length of the projector-lens which projects the image of size 60
$\times $
60 cm of a slide on a screen 2.4 m away, the slide being of the size 3
$\times $
3 cm.
Light enters a prism of angle A at a grazing incidence to emerge at an angle
$\theta $
with the normal. Show that the refractive index of the material of the prism is given by,
$\mu ={\left\{1+{\left(\frac{\mathrm{cos}A+\mathrm{sin}\theta}{\mathrm{sin}A}\right)}^{2}\right\}}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}$
Answer
1
Shubhrajyoti Ghosh
Subject: Physics
, asked on 13/3/18
No links please
Q10. A convex lens of focal length 15 cm is placed in front of a convex mirror. Both are coaxial and the lens is 5 cm from the apex of the mirror. When an object is placed on the axis at distance of 20 cm from the lens, it is found that the image coincides with the object. Calculate the radius of curvature of the mirror.
Answer
1
Shubhrajyoti Ghosh
Subject: Physics
, asked on 13/3/18
No links please Mock Test Papers for H.S. & Competitive Examinations The numerical value of the focal length of a thin convergent lens is f and an object is at a distance u from the lens; a plane mirror is placed behind the lens perpendicular to the axis at a distance f from the lens. The image of the object after reflection at the mirror and a second refraction through the lens is at a distance v in front of the lens. Prove that u + v = 2f
Answer
1
Shubhrajyoti Ghosh
Subject: Physics
, asked on 13/3/18
No links please
A heater is designed to operate with a power of 440 watt in a 220 volt line. A
resistance R is connected parallel with it and the combination is joined in
series with a resistance of 11 ohm to a 220 volt mains. What should be the value
of R so that the heater operates a power of 110 watt?
Answer
1
Shubhrajyoti Ghosh
Subject: Physics
, asked on 13/3/18
No links please:
10. A convex lens is placed between an object and a screen. Two real images are formed due to the positions of the lens. If the length of the real images be I
_{1}
and I
_{2}
, then prove object length is
$I=\sqrt{{I}_{1},{I}_{2}}$
Answer
1
Shubhrajyoti Ghosh
Subject: Physics
, asked on 13/3/18
No links please
If a lens of flint glass of dispersive powers 0.066 be combined with another of crown glass of dispersive power 0.033 and focal length 0.60m to form an achromatic doublet,then what will be the focal length of flint glass lens?
Answer
1
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What are you looking for?

Q. What do you mean by polarisation of light.

Compare between interference and diffraction. Establish Brewster's law.

Q. A compound microscope consists of two lenses of focal lengths 0.8 cm and 3 cm respectively. If the object is 0.85 cm from the objective and the final image is to be 24 cm from the eye-piece, compute the magnifying power of the microscope.

A shot sighted person cannot see distinctly objects beyond 2m from the eye. Find the focal length and the powe rof the spectacle lens which will enable him to see distant objects clearly.

(b)An object is D cm from a screen. A convex lens forms an image of it on the screen. When moved through a distance x cm, it forms another image. Prove that the ratio of the sizes of the two images produced is ${\left(\frac{D+X}{D-X}\right)}^{2}.$Q. State Huygen's principle. In the light of Huygen's principle, explain the refraction of light.

Q.(b) A man can read a newspaper clearly which is placed at a distance 25 cm from the eye with the help of a spectacle of power + 3D. If he wants to read it without spectacle then how far he has to place the newspaper from his eye?

(c)In an aquarium, a fish 6 cm long is swimming directly towards the plane glass front. If, at a certain moment, head of the fish is 18 cm behind the glass front, find the apparent length of the fish as seen by a person looking through the glass. Given R.I. of water =4/3.(b) The focal length of a glass lens in air is 5 cm. What will be its focal length in water ?

$\left\{{\mu}_{g}=1.51,{\mu}_{w}=1.33\right\}$

Q. Find the focal length of the projector-lens which projects the image of size 60$\times $60 cm of a slide on a screen 2.4 m away, the slide being of the size 3$\times $3 cm.

Light enters a prism of angle A at a grazing incidence to emerge at an angle $\theta $ with the normal. Show that the refractive index of the material of the prism is given by,

$\mu ={\left\{1+{\left(\frac{\mathrm{cos}A+\mathrm{sin}\theta}{\mathrm{sin}A}\right)}^{2}\right\}}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}$

Q10. A convex lens of focal length 15 cm is placed in front of a convex mirror. Both are coaxial and the lens is 5 cm from the apex of the mirror. When an object is placed on the axis at distance of 20 cm from the lens, it is found that the image coincides with the object. Calculate the radius of curvature of the mirror.

A heater is designed to operate with a power of 440 watt in a 220 volt line. A

resistance R is connected parallel with it and the combination is joined in

series with a resistance of 11 ohm to a 220 volt mains. What should be the value

of R so that the heater operates a power of 110 watt?

10. A convex lens is placed between an object and a screen. Two real images are formed due to the positions of the lens. If the length of the real images be I

_{1}and I_{2}, then prove object length is $I=\sqrt{{I}_{1},{I}_{2}}$If a lens of flint glass of dispersive powers 0.066 be combined with another of crown glass of dispersive power 0.033 and focal length 0.60m to form an achromatic doublet,then what will be the focal length of flint glass lens?