CBSE Questions for Class 12 Medical Physics Wave Optics Quiz 12 - MCQExams.com

Wave which cannot travel in vacuum is 
  • $$X-$$ rays
  • Infrasonic
  • Ultraviolet
  • Radiowaves
Which of the following statement is wrong
  • Infrared photon has more energy than the photon of visible light
  • Photographic plates are sensitive to ultraviolet rays
  • Photographic plates can be made sensitive to infrared rays
  • Infrared rays are invisible but can cast shadows like visible light rays
In a young's double slit experiment, the central point on the screen is
  • Bright
  • Dark
  • First bright and then dark
  • First dark and then bright
In Young's double slit experiment if $$L$$ is the distance between the slits and the screen upon which interference pattern is observed $$x$$ is the average distance between the adjacent fringes and $$d$$ being the slit separation. The wavelength of light is given by
  • $$\dfrac {xd}{L}$$
  • $$\dfrac {xL}{d}$$
  • $$\dfrac {Ld}{x}$$
  • $$\dfrac {1}{Ldx}$$
In Young's double slit experiment the spacing between two slits is $$0.1\ mm$$. If the screen is kept at a distance of $$1.0\ m$$ from the  from the slits and the wavelength of light is $$5000\ \overset {o}{A}$$, then the fringe width is
  • $$1.0\ cm$$
  • $$1.5\ cm$$
  • $$0.5\ cm$$
  • $$2.0\ cm$$
Wavefront means
  • All particles in it have same phase
  • All particles have opposite phase of vibration
  • Few particles are in same phase, are on opposite phase
  • None of these
The ozone layer absorbs 
  • Infrared radiation
  • Ultraviolet radiation
  • $$X-$$ rays
  • $$\gamma$$- rays
In a Young's double slit experiment $$62$$ fringes are seen in visible region  for sodium light of wavelength $$5893\overset{o}{A}$$. If violet light of wavelength $$4358\overset{o}{A}$$ is used in plane of sodium light, then number of fringes seen will be
  • $$54$$
  • $$64$$
  • $$74$$
  • $$84$$
The range of wavelength of the visible light is 
  • $$10\ A^o$$ to $$100\ A^o$$
  • $$4,000\ A^o$$ to $$8,000\ A^o$$
  • $$8,000\ A^o$$ to $$10,000\ A^o$$
  • $$10,000\ A^o$$ to $$15,000\ A^o$$
What is ozone hole 
  • Hole in the ozone layer
  • Formation of ozone layer
  • Thinning of ozone layer in troposphere
  • Reduction in ozone thickness in stratosphere
In two separate set ups of the Young's double slit experiment, fringes of equal width are observed when lights of wavelength in the ratio $$1:2$$ are used. If the ratio of the slit separation in the two cases is of the distance between the plane of the slits and the screen in the two set ups is
  • $$4:1$$
  • $$1:1$$
  • $$1:4$$
  • $$2:1$$
Which radiation in sunlight, causes heating effect 
  • Ultraviolet
  • Infrared
  • Visible light
  • All of these
Select the right option in the following 
  • Christiaan Huygens a contemporary of Newton established the wave theory of light by assuming that light waves were transverse
  • maxwell provide the compelling theoretical evidence that light is transverse wave
  • Thomas Young experimentally proved the wave behavior of light and Huygens assumption
  • All the statements give above, correctly answer the question "what is light "
The penetration of light into the region of geometrical shadow is called
  • Polarisation
  • Interference
  • Differection
  • Reflection
The phase difference between incident wave and reflected wave is $$180^o$$ when light ray
  • Enters into glass from air
  • Enters into air from glass
  • Enters into glass from diamond
  • Enters into water from glass
Following figure shows sources $$S_{1}$$ and $$S_{2}$$ that emits light of wavelength $$\lambda$$ in all directions. the sources are exactly in phase and are seperated by a distance equal to $$1.5\lambda .$$ If we start at the indicated start point abd travel along path $$1$$ and $$2,$$ the interference produce a maxima all along 
1827476_197da393c8934436b26378f6d855475f.png
  • Path $$1$$
  • Path $$2$$
  • Any path
  • None of these
When a thin metal plate is placed in the path of one of the interfering beams of light
  • Fringe width increase
  • Fringe disappear
  • Fringes becomes brighter
  • Fringes becomes blurred
Which of the following is not a property of light
  • It requires a material medium for propogation
  • It can travel through vacuum
  • It involves transportation of energy
  • It has finite speed
A star emits light of $$5500 \overset{o}{A}$$ wavelength. Its appears blue to an observer on the earth, it means
  • Star is going away from the earth
  • Star is stationary
  • Star is coming towards earth
  • None of the above
A plane wavefront $$(\lambda=6 \times 10^{-7}\ m)$$ falls on a slit $$0.4\ mm$$ wide. A convex lens of focal length $$0.8\ m$$ placed behind the slit focuses the light on a screen. What is the linear diameter of second maximum
  • $$6\ mm$$
  • $$12\ mm$$
  • $$3\ mm$$
  • $$9\ mm$$
If a star is moving towards the earth, then the lines are shifted towards
  • Red
  • Infrared
  • Blue
  • Green
Condition of diffraction is
  • $$\dfrac{a}{\lambda}=1$$
  • $$\dfrac{a}{\lambda} > >1$$
  • $$\dfrac{a}{\lambda} < <1$$
  • None of these
In the Young's double slit experiment, for which colour the fringe width is least
  • Red
  • Green
  • Blue
  • Yellow
Diffraction and interference of light suggest
  • nature of light is electromagnetic
  • Wave nature
  • Nature is quantum
  • Nature of light is transverse
If the separation between slit in Young's double slit experiment is reduced to $$\dfrac 13 rd$$, the fringe width becomes $$n$$ times. The value of $$n$$ is 
  • $$3$$
  • $$\dfrac 13$$
  • $$9$$
  • $$\dfrac 19$$
In a Young's experiment, monochromatic light is used to illuminate the two slits $$A$$ and $$B$$. Interference fringes are observed on a screen placed in front of the slits. Now if a thin glass plate is placed normally in the path of the beam coming from the slit
1827490_60b9640d134241cab21b55b541d56b99.png
  • The fringes will disapear
  • The fringes width will increase
  • The fringes width will increase
  • There will be no change in the fringe width but the pattern shifts
A star is going away from the earth. An observer on the earth will see the wavelength of light coming from the star
  • Decreased
  • Increased
  • Neither decreased nor increased
  • Decreased or increased depending upon the velocity of the star
In order to see diffraction the thickness of the film is
  • $$100\ A^o$$
  • $$10,000\ A^o$$
  • $$1/ mm$$
  • $$1/ cm$$
In the set up shown in fig the two slits, $$S_{1}$$ and $$S_{2}$$ are not equidistant from the slits $$S.$$ The central fringe at $$O$$ is them 
1827495_20b4da5df03147a7a01867e58c595107.png
  • Always bright
  • Always dark
  • Either dark or bright depending on the position of $$S$$
  • Neither dark nor bright.
Specific rotation of sugar solution is $$0.01$$ SI units. $$200\ kgm^{-3}$$ of impure sugar solution is taken in a polarimeter tube of length $$0.25\ m$$ and an optical rotation of $$0.4\ rad$$ is observed. The percentage of purity of sugar is the sample is
  • $$80\%$$
  • $$89\%$$
  • $$11\%$$
  • $$20\%$$
In which of the following is the interference due to the division of wave front
  • Young's double slit experiment
  • Fresnel's biprism experiment
  • Lloyd's mirror experiment
  • Demonstration colours of thin film
Choose correct statement .
In most of the circumtances , the  diffraction of sound is more possible compare to diffraction of light :
  • Medium is necessary for sound propagation
  • Sound waves are longitudinal while light rays are transverse
  • Wavelength of light is very less comparable to wavelength of sound
  • Speed of sound wave order is less than 6 compare to speed of light
To show the phenomenon of interference  we need two sources which emit radiation :
  • Of equal frequency and fixed phase difference
  • Of nearly equal frequency
  • of equal frequency
  • of different wavelength
The $$k$$ line of singly ionised calcium has a wavelength of $$393.3\ nm$$ as measured on earth. In the spectrum of one of the observed galaxies, this spectral line is located at $$401.8\ nm$$. The speed with which the galaxy is moving away from us, will be
  • $$6480\ km/s$$
  • $$3240\ km/s$$
  • $$4240\ km/sec$$
  • $$None\ of\ these$$
According to given figure , in an experiment  , electrons are passed through de-Broglie wavelength order towards a narrow's slit of width d and they are detected at D distance  on a screen . The intensity distribution will be :
In young double slit experiment the maximum intensity of light  is $$ I_{max}$$ then the intensity of light of the path difference  $$ \dfrac{\lambda }{2}$$ will be
  • $$ I_{max}$$
  • $$ \dfrac {Imax}{2}$$
  • $$ \dfrac {Imax}{4}$$
  • zero
Off in the distance, you see the headlights of a car, but they are indistinguishable from the single headlight of a motorcycle. Assume the car's headlights are now switched from low beam to high beam so that the light intensity you receive becomes three times greater. What then happens to your ability to resolve the two light sources?
  • It increases by a factor of $$ 9 . $$
  • It increases by a factor of $$ 3 . $$
  • It remains the same.
  • It becomes one-third as good.
  • It becomes one-ninth as good.
If the point object is moved away from mirror normal to screen then ,

73223.jpg
  • fringe width will increase
  • fringe width will decrease
  • fringe width will first increase then decrease
  • Remain unchanged

Unpolarized light of intensity $$32{\text{W}}{{\text{m}}^{{\text{ - 2}}}}$$ passes through three polarizers such that the transmission axis of the last polarizer is crossed with the first. If the intensity of the emerging light is $$3{\text{W}}{{\text{m}}^{{\text{ - 2}}}}$$, what is the angle between the  axes of the first two polarized is.
  • $${45^0}$$
  • $${60^0}$$
  • $${30^0}$$
  • Zero
Light is incident normally on a diffraction grating through which the first order diffraction is seen at $$32^{\circ}$$. The second order diffraction will be seen at
  • $$48^{\circ}$$
  • $$64^{\circ}$$
  • $$80^{\circ}$$
  • there is no second order diffraction in this case.
If half of reflecting surface of upper part of mirror is painted black, choose correct options from the following

73223.jpg
  • Intensity of maxima and minima will increase
  • Intensity at minima will increase and at maxima, intensity will decrease
  • Intensity at minima will remain zero and at maxima, intensity will decrease
  • Intensity at maxima remains unchanged but at minima, intensity will increase
An aperture of diameter 1.2 mm has been illuminated by monochromatic light. The diffracted light is observed on a screen. When the screen is gradually displaced towards the aperture, the centre becomes dark for the first time at a distance of 30cm from the aperture. The wavelength of light used is :
  • 6000$$A^o $$
  • 4000$$A^o $$
  • 8000$$A^o $$
  • 3000$$A^o $$
In an electron experiment, electrons are made to pass through a narrow slit of width $$'d'$$ comparable to their de Broglie wavelength. They are detected on a screen at a distance D from the slit. Which of the following graphs can be expected to represent the numbers of electron $$'N'$$ detected as a function of the detector position $$'y'$$ ($$y=0$$ corresponds to the middle of the slit)?
21971.png
In a Young's double slit experiment
  • if a point source is placed symmetrically from both the slits then interference will be observed on the

    screen
  • if a point source is placed un-symmetrically from both the slits then interference will be observed on the

    screen.
  • if two slits are illuminated by two independent sources then the interference will be observed on the

    screen.
  • intensity of light at two slits should be same for better contrast
In a single slit diffraction experiment, the width of the slit is made half the original width
  • the width of the central maxima becomes double
  • the width of the central maxima becomes half
  • the width of the central maxima becomes one fourth
  • the width of the central maxima becomes four times.
Microwaves of frequency $$3\times 10^{4}\ MHz$$ and ultrasonic waves of wavelength $$1\ cm$$ are passed through a slit of width $$2\ cm$$. Then
  • diffraction will occur only in microwaves
  • diffraction will occur only in ultrasonic wave
  • diffraction will occur in both but diffraction pattern will be different
  • diffraction will occur in both and diffraction patterns will be identical
In an electron microscope the accelerating voltage is increased from 20 kV to 80 kV, the resolving power of the microscope will change from R to
  • $$2 R$$
  • $$\dfrac{R}{2}$$
  • $$4R$$
  • $$3R$$
Interference pattern is observed at 'P' due to superimposition of two waves coming out from a source 'S' as shown in the figure. The value of 'l' for which maxima is obtained at 'P' is (R is perfect reflecting surface) 
99635.jpg
  • $$l=\dfrac {2n\lambda}{\sqrt 3-1}$$
  • $$l=\dfrac {(2n-1)\lambda}{2(\sqrt 3-1)}$$
  • $$l=\dfrac {(2n-1)\lambda \sqrt 3}{4(2-\sqrt 3)}$$
  • $$l=\dfrac {(2n-1)\lambda}{\sqrt 3-1}$$
Find fringe width and number of possible maxima on the screen $$E$$:
155140_4c357df282e64921b0fbdc6b27558c3c.png
  • $$1.1mm, 8$$
  • $$1.1mm, 9$$
  • $$0.8mm,8$$
  • $$0.9mm,9$$
The shape of the nodal curves is 
  • Elliptical
  • Parabolic
  • Hyperbolic
  • Circular
0:0:1


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