All STD 12 - Wave optics questions
Newest firstShowing 151–177 of 177 questions
- 151. Unpolarized light of intensity \(I\) is incident on a system of two polarizers, \(A\) followed by \(B.\) The intensity of emergent light is \(I/2.\) If a third polarizer \(C\) is placed between \(A\) and \(B,\) the intensity of emergent light is reduced to \(I/3 .\) The angle between the polarizers \(A\) and \(C\) is \(\theta \) . Then 2018 Medium
- 152. Unpolarized light of intensity \(I\) passes through an ideal polarizer \(A\) Another indentical polarizer \(B\) is placed behind \(A\) The intensity of light beyond \(B\) is found to be \(\frac{I}{2}\) Now another identical polarizer \(C\) is placed between \(A\) and \(B\). The intensity beyond \(B\) is now found to be \(\frac{I}{8}\) The angle between polarizer \(A\) and \(C\) is:......\(^o\) 2018 Medium
- 153. A single slit of width \(0.1\, mm\) is illuminated by a parallel beam of light of wavelength \(6000\,\mathop A\limits^o \) and diffraction bands are observed on a screen \(0.5\, m\) from the slit. The distance of the third dark band from the central bright band is........\(mm\) 2017 Medium
- 154. A single slit of width \(b\) is illuminated by a coherent monochromatic light of wavelength \(\lambda \). If the second and fourth minima in the diffraction pattern at a distance \(1\,m\) from the slit are at \(3\, cm\) and \(6\, cm\) respectively from the central maximum, what is the width of the central maximum ?......\(cm\) (i.e. distance between first minimum on either side of the central maximum) 2017 Hard
- 155. An observer is moving with half the speed of light towards a stationary microwave source emitting waves at frequency \(10\ GHz\). What is the frequency of the microwave measured by the observer?.......\(GHz\) ( speed of light \(= 3 \times 10^8 \) \(ms^{-1}\)) 2017 Medium
- 156. In a Young's double slit experiment, slits are separated by \(0.5\ mm\), and the screen is placed \(150\ cm\) away. A beam of light consisting of two wavelengths, \(650\ nm\) and \(520\ nm\), is used to obtain interference fringes on the screen. The least distance from the common central maximum to the point where the bright fringes due to both the wavelengths coincide is...... \(mm\) 2017 Medium
- 157. In Young's double slit experiment, the distance between slits and the screen is \(1 .0\,\,m\) and monochromatic light of \(600\,\,nm\) is being used. A person standing near the slits is looking at the fringe pattern. When the separation between the slits is varied, the interference pattern disappears for a particular distance \(d_0\) between the slits . If the angular resolution of the eye is \(\frac {1}{60}^o,\) the value of \(d_0\) is close to......\(mm\) 2016 Medium
- 158. The box of a pin hole camera, of length \(L\), has a hole of radius \(a\). It is assumed that when the hole is illuminated by a parallel beam of light of wavelength \(\lambda\), the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size ( say \(b_{min}\)) when 2016 Hard
- 159. Two stars are \(10\) light years away from the earth. They are seen through a telescope of objective diameter \(30\, cm\). The wavelength of light is \(600\, nm\). To see the stars just resolved by the telescope, the minimum distance between them should be ( \(1\) light year \(= 9.46 \times 10^{15}\, m\)) of the order of 2016 Medium
- 160. A parallel beam of electrons travelling in \(x-\) direction falls on a slit of width \(d\) (see figure) . If after passing the slit, an electron acquires momentum \(P_y\) in the \(y-\) direction then for a majority of electrons passing through the slit ( \(h\) is Planck's constant)
2015 Medium - 161. Assuming human pupil to have a radius of \(0.25\ cm\) and a comfortable viewing distance of \(25\ cm\), the minimum separation between two objects that human eye can resolve at \(500\ nm\) wavelength is.....\(\mu m\) 2015 Medium
- 162. In a Young's double slit experiment with light of wavelength \(\lambda \) the separation of slits is \(d\) and distance of screen is \(D\) such that \(D >> d >> \lambda \). If the fringe width is \(\beta \). the distance from point of maximum intensity to the point where intensity falls to half of maximum intensity on either side is 2015 Hard
- 163. Unpolarized light of intensity \(I_0\) incident on surface of a block of glass at Brewster's angle. In that case, which one of ihe following statements is true ? 2015 Medium
- 164. A ray of light is incident from a denser to a rarer medium. The critical angle for total internal reflection is \({\theta _{iC}}\) and Brewster's angle of incidence is \({\theta _{iB}}\), such that \(\sin \,{\theta _{iC}}/\sin \,{\theta _{iB}} = \eta = 1.28\). The relative refractive index of the two media is 2014 Medium
- 165. In a Young's double slit experiment, the distance between the two identical slits is \(6.1\) times larger than the slit width. Then the number of intensity maxima observed with in the central maximum of the single slit diffraction pattern is 2014 Medium
- 166. In an experiment of single slit diffraction pattern, first minimum for red light coincides with first maximum of some other wavelength . If wavelength of red light is \(6600\,\mathop A\limits^o\) , then wavelength of first maximum will be.....\(\mathop A\limits^o \) 2014 Medium
- 167. Interference pattern is observed at \('P'\) due to superimposition of two rays coming out from a source \('S'\) as shown in the figure. The value of \('I'\) for which maxima is obtained at \('P'\) is: ( \(R\) is perfect reflecting surface)
2014 Hard - 168. Match List \(− I\) (Event) with List \(−II \) (Order of the time interval for happening of the event) and select the correct option from the options given below the lists
2014 MediumList \(- I\) List \(- II\) \((1)\) Rotation period of earth \((i)\) \(10^5\, s\) \((2)\) Revolution period of earth \((ii)\) \(10^7\, s\) \((3)\) Period of light wave \((iii)\) \(10^{-15}\, s\) \((4)\) Period of sound wave \((iv)\) \(10^{-3}\, s\) - 169. The diameter of the objective lens of microscope makes an angle \(\beta \) at the focus of the microscope. Further, the medium between the object and the lens is an oil of refractive index \(n\). Then the resolving power of the microscope 2014 Medium
- 170. Two beams, \(A\) and \(B\), of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position when the beam \(A\) has maximum intensity ( and beam \(B\) has zero intensity), a rotation of polaroid through \(30 ^o \) makes the two beams appear equally bright. If the initial intensities of the two beams are \(I_A\) and \(I_B\) respectively, then \(\frac{{{I_A}}}{{{I_B}}}\)= 2014 Medium
- 171. Two monochromatic light beams of intensity \(16\) and \(9\) units are interfering . The ratio of intensities of bright and dark parts of the resultant pattern is 2014 Hard
- 172. Using monochromatic light of wavelength \(\lambda \), an experimentalist sets up the Young 's double slit experiment in three ways as shown. If she observes that \(y = \beta '\), the wavelength of light used is.....\(nm\)
2014 Hard - 173. A person lives in a high-rise building on the bank of a river \(50\, m\) wide. Across the river is a well lit tower of height \(40\, m\). When the person, who is at a height of \(10\, m\), looks through a polarizer at an appropriate angle at light of the tower reflecting from the river surface, he notes that intensity of light coming from distance \(X\) from his building is the least and this corresponds to the light coming from light bulbs at height \('Y'\) on the tower. The values of \(X\) and \(Y\) are respectively close to (refractive index of water \( \simeq \frac{4}{3})\)
2013 Hard - 174. A ray of light of intensity \(I\) is incident on a parallel glass slab at point \(A\) as shown in diagram. It undergoes partial reflection and refraction. At each reflection, \(25\%\) of incident energy is reflected. The rays \(AB\) and \(A'B'\) undergo interference. The ratio of \(I_{max}\) and \(I_{min}\) is
2013 Hard - 175. \(n\) identical waves each of intensity \(I_0\) interfere with each other. The ratio of maximum intensities if the interference is \((i)\) coherent and \((ii)\) incoherent is : 2013 Medium
- 176. This question has Statement \(-1\) and Statement \(-2.\) Of the four choices given after the Statements, choose the one that best describes the two Statements. Statement \(-1:\) In Young's double slit experiment, the number of fringes observed in the field of view is small With longer wavelength of light and is large with shorter wavelength of light. Statement \(-2:\) In the double slit experiment the fringe width depends directly on the wavelength of light. 2013 Easy
- 177. Two coherent point sources \(S_1\) and \(S_2\) are separated by a small distance '\(d\)' as shown. The fringes obtained on the screen will be
2013 Easy
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