| 1 |
Which of the following is an optical fibre in which the density of central core decreases towards its periphery? |
multi-mode step index fibre
multi-mode graded index fibre
both of them
none of them
|
| 2 |
In multi-mode step index optical fibre, that layer is called cladding which has |
higher refractive index
lower refractive index
both of them
none of them
|
| 3 |
The multi-mode step index optical fibre, the central core has |
high refractive index and low density
low refractive index and density
low refractive index and low density
high refractive index and high density
|
| 4 |
Most widely used optical fibres are those which propagate light by |
total interval reflection
continuous refraction
both of them
none of them
|
| 5 |
The light signal in an optical fibre is totally confined due to the |
total internal reflection
continuous refraction
both of them
either of them
|
| 6 |
The light signal in an optical fibre requires that the light should |
be partially confined within the fibre
be totally confined within the fibre
not be confined within the table
none of them
|
| 7 |
Propagation of light in an optical fibre requires that the light should |
be partially confined within the fibre
be totally confined within the fibre
not be confined within the table
none of them
|
| 8 |
The diameter of an optical fibre with its protective case may be typically |
7.62 cm
67.62 mm
6.0 mm
90 mm
|
| 9 |
The information carrying capacity in an optical fibre is called |
wavelength
frequency
bandwidth
none of them
|
| 10 |
For a system to transmit thousands of telephones conversations, several television programs and numerous data signals, it need the following number so threads of optical fibre |
100 to 200
1000 to 10000
100 to 1000
1 or 2
|
| 11 |
Which of the following cannot be polarized? |
x-rays
light rays
sound waves
ultraviolet rays
|
| 12 |
When light passes through a tourmaline crystal, it becomes |
plane polarized
directly polarized
un-polarized
spherically polarized
|
| 13 |
Reflection of light from water, glass, snow and rough road surfaces, for larger angle of incidences, produces |
images
bright images
interference
glare
|
| 14 |
Which of the following phenomenon cannot take place if we consider light as longitudinal wave? |
diffraction
interference
polarization
reflection
|
| 15 |
Which property of waves proves that light is a transverse wave? |
diffraction
interference
polarization
reflection
|
| 16 |
The materials which are used in selective absorption method to polarize the light are |
chronic substances
organic substances
inorganic substances
diachronic substance
|
| 17 |
Which of the following is the most common method to obtain polarized light? |
selective absorption
reflection from different surfaces
refraction through crystals
scattering by small particles
|
| 18 |
If the vibrations of the light wave are confined to one plane only, then this light is called |
unpolarized ligth
polarized light
sunlight
none of them
|
| 19 |
The light which has components in all directions is called |
unpolarized light
polarized light
intense light
none of them
|
| 20 |
Ordinary light has components of vibrations in |
one direction only
two directions
four directions
all directions
|
| 21 |
In light waves, the components of electric and magnetic fields are |
parallel to each other
anti-parallel to each
right angle to each other
none of them
|
| 22 |
A light wave produced by oscillating charge consists of a periodic variation of |
electric field
magnetic field
either of them
both of them
|
| 23 |
The wavelength of light is 6000°A, the number of waves continued in 0.01 m distance will be |
1.6 x 10<sup>4</sup>
3 x 10<sup>3</sup>
2 x 10<sup>6</sup>
4 x 10<sup>8</sup>
|
| 24 |
One angshom is equal to? |
10<sup>-8</sup>cm
10<sup>-6</sup>m
10<sup>-10</sup>nm
10<sup>-8</sup>nm
|
| 25 |
Wavelength of X-rays falling at glace angle 30° on crystal with atomic spacing 2 x 10-9m for the first order diffraction is |
4 x 10<sup>-6</sup>m
2 x 10<sup>-10</sup>m
0.2 x 10<sup>-10</sup>m
20 x 10<sup>-10</sup>m
|
| 26 |
When a mirror of a Michelsion's interferometor is moved a distance of 0.5 mm, 2000 fringes are observed, the wavelength of the light used is |
5000 mm
5000<span style="color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;">°A</span>
500 cm
2000<span style="color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;">°A</span>
|
| 27 |
For the monochromatic beam of X-rays, the crystal planes in a lattice act like a |
perfect absorbers
boundary
mirror
none of them
|
| 28 |
The study of atomic structures of crystals by X-rays was started in |
1890
1905
1914
1944
|
| 29 |
The regular array of atoms in a crystal has spacing of the order of |
10<sup>-16</sup>m
10<sup>-14</sup>m
10<sup>-10</sup>m
10<sup>-6 </sup>m
|
| 30 |
We can observe only when the grating spacing is |
of the order of the wavelength used
greater than the wavelength used
less than the wavelength used
any one of them
|
| 31 |
The wavelength of X-rays is about |
10<sup>-14</sup>m
10<sup>-10</sup>m
10<sup>-6</sup>m
10<sup>-4</sup>m
|
| 32 |
A diffraction grating has 500 liens per mm. its slit spacing or grating element will |
500 mm
5 x 10<sup>-3 </sup>mm
2 x 10<sup>-5</sup>mm
2 x 10<sup>-3</sup>mm
|
| 33 |
If 5000 lines per cm are ruled on different on a diffraction grating then the slit spacing will be |
5 x 10<sup>-3</sup>A<span style="color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;">°</span>
2 x 10<sup>-4</sup>A<span style="color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;">°</span>
5 x 10<sup>-5</sup>A<span style="color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;">°</span>
2 x 10<sup>4</sup>A<span style="color: rgb(84, 84, 84); font-family: arial, sans-serif; font-size: small;">°</span>
|
| 34 |
A diffraction grating contains 5000 lines per centimeter, its grating element will be |
1 x 10<sup>-4</sup>nm
1 x 10<sup>-14</sup>m
1 x 10<sup>-14</sup>cm
1 x 10<sup>-4</sup>cm
|
| 35 |
The diffraction grating is used to measure |
wavelength of light
focal length of a lens
refractive index of prism
polarization of light
|
| 36 |
The spacing between the parallel lines are served as |
slits
source of light
opaque lines
fringes
|
| 37 |
A glass plate on which a large number of very fine equidistant parallel lines are drawn is called |
convex lens
thin film
diffraction grating
interferometer
|
| 38 |
The distance between the top adjacent slits on diffraction grating is called |
element
grating element
aperture
slit
|
| 39 |
A typical diffraction grating has lines per centimeter |
10 to 100
100 to 1000
1000 to 5000
400 to 5000
|
| 40 |
On a diffraction grating which thing acts as a slit |
the lines which are ruled on it
the spacing between the lines
either of them
none of them
|