119 practice sets · Page 6 of 6
In Fraunhofer diffraction pattern for single slit, a central maximum is obtained when angle of diffraction q is equal to zero. What it actually indicates?
All the diffracted rays are parallel and focused by slit at a single point on screen
All the diffracted rays are perpendicular and focused by slit at a single point on screen
The rays are diffracted by the slit in all the directions
The rays are reflected by the slit
In diffraction pattern of monochromatic light the bright bands formed are
of uniform intensity
of non-uniform intensity
of uniform width
is of different colors
In diffraction Fraunhofer diffraction pattern due to single slit central maxima is formed at center because
Lens focuses all the diffracted rays at the centre of the slit
Slit focuses all the diffracted rays at the centre of the slit
Light rays focused at the centre of the screen undergo constructive interference
Slit and lens both combined focuses the rays at the centre of the slit
In case of thin film of non-uniform thickness, when illuminated with white light, the film appears colored. This is due to change of what factor?
Conditions for path difference at different points of film
Change in optical path difference at different points of film
Thickness of film is different at different points of film
All of above
In a Youngs double-slit experiment the center of a bright fringe occurs wherever waves from the slits differ in the distance they travel by a multiple of
a fourth of a wavelength
a half a wavelength
a wavelength
three-fourths of a wavelength
In a longitudinal wave
The particles move parallel to the direction of the wave motion.
The particles move perpendicular to the direction of the wave motion.
Energy causes the particles to move forward with the wave.
Energy is propagated by crests and troughs.
If you look perpendicular at thin film and move yourself away from the film (staying perpendicular to the film), you will notice
Reflected light becomes brighter and brighter
Reflected light becomes darker and darker
Reflected light alternates between darker and brighter
None of the Above
If we narrow the distance between two slits in Youngs experiment the fringes width
Increases
Decreases
Remains same
becomes zero
How the intensity of secondary maxima varies in case of Fraunhofer diffraction pattern for single slit?
Intensity of secondary maxima decreases on either sides
Intensity of secondary maxima remains constant on either side
Intensity increases and decreases alternately
Intensity of secondary maxima increases on either sides
Fringe spacing is defined as the distance between two Consecutive
Crests
Bright fringes only
Dark fringes only
Bright or dark fringes
Fresnels type diffraction is observed when
Only screen is placed at finite distance
Only source is placed at finite distance
Both source and screen are at finite distance
Neither source nor screen is at finite distance
Fraunhofer diffraction is observed when
Only screen is placed at finite distance
source is placed at finite distance
neither source nor screen is at finite distance
None of these
Fraunhofer diffraction at a Plane Grating. What is the meaning of grating element for a diffraction grating?A It is the width of a single slit
It is the width of the opaque space
It is the distance between two slits
It is the width of diffraction grating
For all transparent material substances, the index of refraction
is less than 1
is greater than 1
is equal to 1
Could be any of the given answers; it all depends on optical density
Find the maximum value of resolving power of a grating 3 cm wide having 5000 lines per cm, if the wavelength of light used is 5890 Ao.
40000
45000
4500
5000
Extended source is needed in
Youngs double slit experiment
Bi prism Experiment
Newtons Ring Experiment
None of them
Diffraction is special type of
Reflection
Refraction
Interference
Polarization
Diffraction due to circular aperture If a light passes through a small pinhole, and incident on a screen. What will be observed on the screen?
A sharp bright point of the width equal to width the pinhole
A bright point of the width equal to width the pinhole but of less intensity
A bright ring at the centre surrounded by alternate dark and bright rings
A diffused bright point
Colors in thin films are because of
Dispersion
Compton effect
Interference
Diffraction
