Case Study Questions Class 12 Physics Chapter 10 Wave Optics
CBSE Class 12 Case Study Questions Physics Wave Optics. Term 2 Important Case Study Questions for Class 12 Board Exam Students. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions Wave Optics.
At Case Study Questions there will given a Paragraph. In where some Important Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks, 4 marks.
CBSE Case Study Questions Class 12 Physics Wave Optics
Case study 1:
According to superposition principle, the resultant displacement produced due the number of waves at a particular point is the vector sum of displacement produced by the each vector at that point. The two sources of light are said to be coherent only when the phase difference between the light waves produced by them is zero or constant. The point at which two waves are in phase or if trough of one wave coincides with the trough of other or crest of one wave coincides with the crest of other then the resultant intensity produced at that point will be larger and amplitude also maximum. Such points are the points where constructive interference takes place. While there are some points where two light waves are not in phase with each other and crest of one wave coincides with the trough of other and vice versa due to which resultant intensity at that point is minimum and amplitude also get decreased. Such points are the points where destructive interference takes place.
For constructive interference, the path difference is equal to integral multiple of wavelengths and resultant intensity will be maximum at that points. While for destructive interference, the path difference is (n + 1/2) multiple of wavelengths and where resultant intensity is zero. When light is passed around the sharp edges of an obstacle it get bended and may enters into the geometrical shadow of that obstacle such a phenomenon of light is called as diffraction of light. In interference, there are equally spaced alternate bright and dark bands are possible. While in diffraction, the there is a only one bright central Maxima and around both sides of the central Maxima the intensity of the light decreases as we go away from that central Maxima.
Questions:
Q 1.) For coherent sources of light the phase difference must be___
a) one
b) zero
c) either zero or constant
d) 90°
Q 2.) If the phase difference is 0, +2π, -4π then the interference should be
a) constructive interference
b) destructive interference
c) both a and b
d) diffraction of light
Q 3.) For destructive interference
a) path difference is (n +1/2) times wavelength
b) phase difference is π, -3π, +5π
c) path difference is integral multiple of wavelengths
d) both a and b
Q 4.) The interference and diffraction of light explains which nature of light?
Q 5.) How conservation of energy is possible in interference and diffraction of light?
Answer key:
Q 1.) c) either zero or constant
Q 2.) a) constructive interference
Q 3.) d) both a and b
Q 4.) The phenomenon of interference of light and diffraction of light explains the wave nature light.
Q 5.) In interference and diffraction of light, there is a redistribution of light energy takes place. That means if a dark fringe with less light energy is produced then there will be also a bright fringe with high light energy will be produced in the another region. Therefore there will be no loss or gain in light energy takes place which obeys the law of conservation of energy.
Case study 2:
We know that, light waves are electromagnetic waves which are transverse in nature and having constant speed equal to 3*108m/s. The electric field vector and magnetic field vector are mutually perpendicular to each other and also perpendicular to the direction of propagation in Electromagnetic Waves. The light coming from the sun is the unpolarised light because electric filed vectors are oriented in all directions. When a unpolarised light is passed through the Polaroids, the Polaroids passes the light vectors which are vibrating along the axis of the Polaroid and the light coming out from it is called as the plane polarised light. But when such a plane polarised light is passed through the Polaroid whose axis is not along the light vectors of plane polarised light then there will be no light came out through the Polaroid. Polarisation of light can occur by reflection and scattering of light also. In case of polarisation by reflection, when an unpolarised light is incident on the interface separating two transparent media then the reflected light is polarised light whose light vectors are perpendicular to the plane of incidence only when reflected and refracted rays makes an angle of 90°. And in such case, for which angle between reflected and refracted ray is 90°, the reflected light is totally get polarised. And the angle of incidence for which the reflected wave get totally polarised is called as Brewster’s angle and denoted as iB.
Questions:
Q 1.) Polarisation of light also takes place by reflection only when angle of incidence is ____
a) 90°
b) critical angle
c) Brewster’s angle
d) less than 90°
Q 2.) The polarization of light can be takes place when light is scattered through ____ in the atmosphere.
a) π
b) less than π
c) π/2
d) 2π
Q 3.) Polarisation of light explains the _____ nature of light.
a) particle
b) photon
c) wave
d) both wave and particle
Q 4.) What is the Brewster’s law?
Q 5.) What are the uses of Polaroids?
Answer key:
Q 1.) c) Brewster’s angle
Q 2.) c) π/2
Q 3.) c) wave
Q 4.) Brewster’s law gives the relationship between refractive index of the medium and the Brewster’s angle which is stated as u = taniB.
Where, u is the refractive index of the medium
And iBis the Brewster’s angle
Q 5.) There are many applications of Polaroids such as to control the intensity of in sunglasses and in windowpanes. They are also used in 3D movie cameras and also in photographic cameras.