Eamcet - Physics - Optics

The focal length of an equi-convex lens is greater than the radius of curvature of any of the surfaces. Then the refractive index of the material of the lens is :

A.  greater than zero but less than 1.5

B.  greater than 1.5 but less than 2.0

C.  greater than 2.0 but less than 2.5

D.  greater than 2.5 but less than 2.0

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Fraunhofer lines are produced by the absorption of light in :

A.  The chromosphere of the sun

B.  The photosphere of the sun

C.  Sodium

D.  Hydrogen

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According to Moselay's law, the frequency of  (v) of the Kα - line and the atomic number (Z) of the element  have the relation (A and B are constants)

A.  v / (Z - A) = B

B.  √ν / (Z - A) = B

C.  v (Z - A) = B

D.  v (Z - A)2 = B

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The angle of a prism is 600 and the angle of minimum deviation of light passing through it is observed to be 400. The angle of incidence of light is

A.  300

B.  400

C.  500

D.  600

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In a Ramsden eyepiece of effective focal length 3 cm the focal length of eye lens, in cm, is :

A.  1.5

B.  8/3

C.  3

D.  4

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If a is the radius of first Bohr orbit in hydrogen atom, the radius of 3rd orbit is :

A.  3a

B.  9a

C.  27a

D.  81a

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Photoelectric current can be increased by using :

A.  higher frequency radiation

B.  higher intensity radiation

C.  higher work function of metal plates

D.  none of the above

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The refractive index of the material of a double convex lens is 1.5 and its focal length is 5 cm. If the radii of curvature are equal, the value of the radius of curvature (in cm) is

A.  5.0

B.  6.5

C.  8.0

D.  9.5

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In Ramsden eyepiece, the two planoconvex lenses each of focal length / are separated by a distance 12 cm. The equivalent focal length (in cm) of the eyepiece is

A.  10.5

B.  12.0

C.  13.5

D.  15.5

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In Huygen's eyepiece

A.  the cross wires are outside the eyepiece

B.  condition for achromatism is satisfied

C.  condition for minimum spherical aberration is not satisfied

D.  the image formed by the objective is a virtual image

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The work function of the nickel is 5 eV. When a light of wavelength 2000 Ao falls on it, it emits photo electrons in the circuit. Then the potential difference necessary to stop the fastest electrons emitted is (given h = 6.67 x  10-34 J-s)

A.  1.0 V

B.  1.75 V

C.  1.25 V

D.  0.75 V

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In an experiment on photoelectric emission from a metallic surface, wavelength of incident light is 2xl0-7 m and stopping potential is 2.5 V. The threshold frequency of the metal (in Hz)   approximately   (charge  of electron e= 1.6 x 10-19 C  Planck's constant h = 6.67 x 10-34 J-s)

A.  12 x 1015

B.  9 x 1015

C.  9 x 1014

D.  12 x 1013

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A motor of power P0 is used to deliver water at a certain rate through a given horizontal pipe. To increase the rate of flow of water through the same pipe n times, the power of the motor is increased to P1 The ratio of P1 to P0 is

A.  n:1

B.  n2 : 1

C.  n3 :  1

D.  n4   : 1

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The two surfaces of a biconvex lens has same radii of curvatures. This lens is made of glass of refractive index 1.5 and has a focal length 10 cm in air. The lens is cut into two equal halves along a plane perpendicular to its principal axis to yield two plano-convex lenses. The two pieces are glued such that the convex surfaces touch each other. If this  combination lens is immersed in water (refractive index = 4/3), its focal length (in cm) is :

A.  5

B.  10

C.  20

D.  40

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Dispersive power depends on the following :

A.  material of the prism

B.  shape of the prism

C.  size of the prism

D.  size, shape and material of the prism

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Match the appropriate pairs from Lists I and II: List-I List-II 1.NItrogen molecules A.continuous spectrum 2.Incandescent solids B.Absorption spectrum 3.Fraunhoffer lines C.Band spectrum 4.Electric arc between iron rods D.Emission spectrum

A.  1-C,2-A,3-B,4-D

B.  1-B, 2-A, 3-D, 4-C

C.  1-D, 2-A, 3-B, 4 -C

D.  1-A, 2-C, 3-D, 4 -B

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The two lenses of an achromatic doublet should have

A.  equal powers

B.  equal dispersive powers

C.  equal ratio of their power and dispersive power

D.  sum of the products of their power and dispersive power should be equal to zero

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The work function of a certain metal is 3.31 x 10-19 J. Then the maximum kinetic energy of photo electrons emitted by incident radiation of wavelength 5000 A0 is

A.  2.48 eV

B.  0.41 eV

C.  2.07 eV

D.  0.82 eV

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Which of the following statements is not true in the case of 1 Huygen's eye piece

A.  It is achromatic

B.  It satisfies condition for minimum spherical aberration

C.  It has cross wires

D.  It cannot be used for measurement

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The locus of the centre of a circle which cuts the circles 2x2+2y2-x-7=0 and 4x2+4y2-3x-y=0 orthogonally is a straight line whose slope is

A.  -1

B.  1

C.  -2

D.  -5/2

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The dispersive powers of the materials of two lenses forming an achromatic combination are in the ratio of 4:3. Effective focal length of the two lenses is +60 cm then the focal lengths of the lenses should be

A.  - 20 cm, 25 cm

B.  - 15 cm, 20 cm

C.  - 15 cm, 20 cm

D.  15 cm, - 20 cm

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If c is velocity of light in fre space,the time taken by the light to travel a distance x in a medium of refractive index μ is given by:

A.  μxc

B.  μx/c

C.  μc/x

D.  x/μ

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If the angle of minimum deviation produced by equilateral prism is 300.The refractive index of the prism is

A.  √2

B.  1.5

C.  1.6

D.  √3

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The ratio of effective focal length of Huygens eye piece and the object distance of its field lens is

A.  3:1

B.  2:3

C.  2:1

D.  1:1

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Photons of energy 2.0 eV and wavelength λ fall on a metal plate and release photoelectrons with a maximum velocity v.By decreasing X by 25% the maximum velocity of photoelectrons is doubled. The work function of the material of the metal plate,in eV is:

A.  2.22

B.  1.985

C.  2/35

D.  1.80

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If the angle of minimum deviation produced by an equilateral prosm is 300, the refractive index of material of prism is

A.  √2

B.  1.5

C.  1.6

D.  √3

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The least distance of distinct vision is 25cm. If the focal length of convex lens is 10 cm. It acts as a simple microscope of maximum magnification

A.  2.5

B.  3

C.  3.5

D.  5

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Consider the two following statements A and B,and identify the correct choice given in the answers:A) In photovoltaic cells the photoelectric current produced is not proportional to the Intensity of Incident light (B) In gas filled photo emissive cells, the velocity of photo-electrons depends on the wavelength of the incident radiation

A.  both A and B are true

B.  both A and B are false

C.  A is true but B is false

D.  A is false but B is true

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The following phenomenon which is not explained by Huygens construction of wave front is

A.  Origin of spectra

B.  Diffraction

C.  Reflection

D.  Refraction

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The distances between the objective and the eye lens of an astronomical telescope when adjusted for parallel light is 100cm.The measured value of the magnification is 19.The focal length of objective and eye piece are

A.  50cm and 50cm

B.  95cm and 5cm

C.  82cm and 18cm

D.  85cm and 15cm

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