Science (English Medium)
Academic Year: 2021-2022
Date & Time: 20th May 2022, 10:30 am
Duration: 2h
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General Instructions:
Read the following instructions carefully and strictly follow them
- This Question paper contains 12 questions. All questions are compulsory.
- This question paper is divided into THREE Sections, Sections A, B, and C.
- Section - A: Question number 1 to 3 are of 2 marks each.
- Section - B: Question number 4 to 11 are of 3 marks each.
- Section - C: Question number 12 is a case-based question of 5 marks.
- There is no overall choice in the question paper. However internal choice has been provided in some of the questions. Attempt any one of the alternatives in such questions.
- Use of log tables is permitted, if necessary, but use of a calculator is not permitted.
c = 3 × 108 m/s
h = 6.63 × 10-34 Js
e = 1.6 × 10-19C
μ0 = 4π × 10-7T m A-1
ε0 = 8.854 × 10-12C2N-1m-2
`1/(4piε_0) = 9 xx 10^9 Nm^2C^-2`
Mass of electron = (me) = 9.1 × 10-31 kg
Mass of Neutron = 1.675 × 10-27kg
Mass of proton = 1.673 × 10-27kg
Avogadro's number = 6.023 × 1023 per gram mole
Boltzmann constant = 1.38 × 10-23 Jk-1
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What is meant by doping of an intrinsic semiconductor?
Chapter: [0.14] Semiconductor Electronics - Materials, Devices and Simple Circuits
Name the two types of atoms used for doping of Ge/Si.
Chapter: [0.14] Semiconductor Electronics - Materials, Devices and Simple Circuits
Distinguish between isotopes and isobars.
Chapter: [0.13] Nuclei
Two nuclei have different mass numbers A1 and A2. Are these nuclei necessarily the isotopes of the same element? Explain.
Chapter: [0.13] Nuclei
Name the factors on which photoelectric emission from a surface depends.
Chapter: [0.11] Dual Nature of Radiation and Matter
Answer the following question.
Define the term "Threshold frequency", in the context of photoelectric emission.
Chapter: [0.11] Dual Nature of Radiation and Matter
Name the extrinsic semiconductors formed when pure germanium is doped with a trivalent impurity. Draw the energy band diagram of extrinsic semiconductors so formed.
Chapter: [0.14] Semiconductor Electronics - Materials, Devices and Simple Circuits
Name the extrinsic semiconductors formed when pure germanium is doped with a Pentavalent impurity. Draw the energy band diagram of extrinsic semiconductors so formed.
Chapter: [0.14] Semiconductor Electronics - Materials, Devices and Simple Circuits
State Bohr's postulate to explain stable orbits in a hydrogen atom. Prove that the speed with which the electron revolves in nth orbit is proportional to `(1/"n")`.
Chapter: [0.12] Atoms
The work function of a metal is 2.31 eV. Photoelectric emission occurs when the light of frequency 6.4 × 1014 Hz is incident on the metal surface. Calculate
- the energy of the incident radiation,
- the maximum kinetic energy of the emitted electron and
- the stopping potential of the surface.
Chapter: [0.11] Dual Nature of Radiation and Matter
A beam of light consisting of two wavelengths 600 nm and 500 nm is used in Young's double slit experiment. The silt separation is 1.0 mm and the screen is kept 0.60 m away from the plane of the slits. Calculate:
- the distance of the second bright fringe from the central maximum for wavelength 500 nm, and
- the least distance from the central maximum where the bright fringes due to both wavelengths coincide.
Chapter: [0.1] Wave Optics
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In a diffraction pattern due to a single slit, how will the angular width of the central maximum change, if orange light is used in place of green light?
Justify your answer.
Chapter: [0.1] Wave Optics
In a diffraction pattern due to a single slit, how will the angular width of the central maximum change, if the screen is moved closer to the slit?
Justify your answer.
Chapter: [0.1] Wave Optics
In a diffraction pattern due to a single slit, how will the angular width of the central maximum change, if the slit width is decreased?
Justify your answer.
Chapter: [0.1] Wave Optics
Answer the following question.
Under what conditions are total internal reflection possible? Explain it with a suitable example.
Chapter: [0.09] Ray Optics and Optical Instruments
Two prisms ABC and DBC are arranged as shown in the figure.
The critical angles for the two prisms with respect to air are 41.1° and 45° respectively. Trace the path of the ray through the combination.
Chapter: [0.09] Ray Optics and Optical Instruments
An object is placed in front of a converging lens. Obtain the conditions under which the magnification produced by the lens is
- negative and
- positive.
Chapter: [0.09] Ray Optics and Optical Instruments
A point object is placed at O in front of a glass sphere as shown in figure.
Show the formation of the image by the sphere.
Chapter: [0.09] Ray Optics and Optical Instruments
A point object is placed at O in front of a glass sphere as shown in figure.
Show the formation of the image by the sphere.
Chapter: [0.09] Ray Optics and Optical Instruments
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James Chadwick, in 1932 studied the emission of neutral radiations when Beryllium nuclei were bombarded with alpha particles. He concluded that emitted radiations were neutrons and not photons. Explain.
Chapter: [0.13] Nuclei
Two nuclei may have the same radius, even though they contain different numbers of protons and neutrons. Explain.
Chapter: [0.13] Nuclei
The energy of hydrogen atom in an orbit is −1.51 eV. What are the kinetic and potential energies of the electron in this orbit?
Chapter: [0.12] Atoms
The electron in a hydrogen atom is typically found at a distance of about 5.3 × 10−11 m from the nucleus which has a diameter of about 1.0 × 10−15 m. Assuming the hydrogen atom to be a sphere of radius 5.3 × 10−11 m, what fraction of its volume is occupied by the nucleus?
Chapter: [0.12] Atoms
| A compound microscope consists of two converging lenses. One of them, of smaller aperture and smaller focal length, is called objective and the other of slightly larger aperture and slightly larger focal length is called eye-piece. Both lenses are fitted in a tube with an arrangement to vary the distance between them. A tiny object is placed in front of the objective at a distance slightly greater than its focal length. The objective produces the image of the object which acts as an object for the eye-piece. The eye-piece, in turn, produces the final magnified image. |
In a compound microscope, the images formed by the objective and the eye-piece are respectively.
virtual, real
real, virtual
virtual, virtual
real, real
Chapter: [0.09] Ray Optics and Optical Instruments
| A compound microscope consists of two converging lenses. One of them, of smaller aperture and smaller focal length, is called objective and the other of slightly larger aperture and slightly larger focal length is called eye-piece. Both lenses are fitted in a tube with an arrangement to vary the distance between them. A tiny object is placed in front of the objective at a distance slightly greater than its focal length. The objective produces the image of the object which acts as an object for the eye-piece. The eye-piece, in turn, produces the final magnified image. |
The magnification due to a compound microscope does not depend upon ______.
the aperture of the objective and the eye-piece
the focal length of the objective and the eye-piece
the length of the tube
the colour of the light used
Chapter: [0.09] Ray Optics and Optical Instruments
| A compound microscope consists of two converging lenses. One of them, of smaller aperture and smaller focal length, is called objective and the other of slightly larger aperture and slightly larger focal length is called eye-piece. Both lenses are fitted in a tube with an arrangement to vary the distance between them. A tiny object is placed in front of the objective at a distance slightly greater than its focal length. The objective produces the image of the object which acts as an object for the eye-piece. The eye-piece, in turn, produces the final magnified image. |
Which of the following is not correct in the context of a compound microscope?
Both lenses are of short focal lengths.
The magnifying power increases by decreasing the focal lengths of the two lenses.
The distance between the two lenses is more than (fo + fe)·
The microscope can be used as a telescope by interchanging the two lenses.
Chapter: [0.09] Ray Optics and Optical Instruments
| A compound microscope consists of two converging lenses. One of them, of smaller aperture and smaller focal length, is called objective and the other of slightly larger aperture and slightly larger focal length is called eye-piece. Both lenses are fitted in a tube with an arrangement to vary the distance between them. A tiny object is placed in front of the objective at a distance slightly greater than its focal length. The objective produces the image of the object which acts as an object for the eye-piece. The eye-piece, in turn, produces the final magnified image. |
A compound microscope consists of an objective of 10X and an eye-piece of 20X. The magnification due to the microscope would be:
2
10
30
200
Chapter: [0.09] Ray Optics and Optical Instruments
| A compound microscope consists of two converging lenses. One of them, of smaller aperture and smaller focal length, is called objective and the other of slightly larger aperture and slightly larger focal length is called eye-piece. Both lenses are fitted in a tube with an arrangement to vary the distance between them. A tiny object is placed in front of the objective at a distance slightly greater than its focal length. The objective produces the image of the object which acts as an object for the eye-piece. The eye-piece, in turn, produces the final magnified image. |
The focal lengths of the objective and eye-piece of a compound microscope are 1.2 cm and 3.0 cm respectively. The object is placed at a distance of 1.25 cm from the objective. If the final image is formed at infinity, the magnifying power of the microscope would be:
100
150
200
250
Chapter: [0.09] Ray Optics and Optical Instruments
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