Wave Optics

35 solved questions from Class 12 Physics, each with the full working. Tap any question to see the step-by-step solution.

• 1 What is the fundamental law or governing principle of 'Wave Optics' in Class 12 Physics? medium MCQ Fundamental Physical Law
• 2 What is the SI unit and dimensional formula for the key physical quantity studied in 'Wave Optics'? medium MCQ SI Units & Dimensional Analysis
• 3 How does the field or potential intensity vary with distance r in 'Wave Optics'? medium MCQ Spatial Distance Dependence
• 4 What is the net flux or circulation integral through a closed surface in 'Wave Optics'? medium MCQ Gauss's Theorem & Boundary Integrals
• 5 Why do field lines in 'Wave Optics' never intersect each other? medium MCQ Field Line Properties
• 6 A single‑slit of width 0.02 cm is illuminated by light of wavelength 500 nm. Find the smallest angle θ (in degrees) at which a minimum in the diffraction pattern occurs. medium 3 marks Single‑slit diffraction minima
• 7 A diffraction grating has a spacing of 5 µm. A monochromatic light of wavelength 650 nm falls on it. Calculate the angle θ (in degrees) at which the third order maximum (m = 3) appears. hard 4 marks Diffraction grating equation
• 8 Two spectral lines at wavelengths 589 nm and 590 nm are produced by a sodium lamp. They are to be resolved using a diffraction grating with line spacing 2 µm. Using the first order maxima (m = 1) and Rayleigh’s criterion, find the minimum number of lines N required on the grating to resolve these two lines. Explain the principle behind the calculation. hard 5 marks Rayleigh criterion & grating resolving power
• 9 In a Young’s double‑slit experiment, the distance between the slits is 0.15 mm, the wavelength of light used is 600 nm, and the screen is placed 1.2 m from the slits. What is the distance between adjacent bright fringes on the screen? easy MCQ 2 marks Young’s double‑slit fringe spacing
• 10 A diffraction grating has N = 5000 lines per centimetre. Monochromatic light of wavelength λ = 480 nm falls normally on the grating. What is the angle θ (in degrees) at which the second order (m=2) maximum is observed? medium MCQ 2 marks Diffraction grating second‑order angle
• 11 A single slit of width a = 0.04 mm is illuminated by monochromatic light of wavelength λ = 600 nm. The screen is placed D = 2.0 m behind the slit. Determine the linear width w of the central bright fringe on the screen. medium 3 marks Single‑slit central maximum width
• 12 In a Young’s double‑slit experiment the slit separation is d = 0.20 mm and monochromatic light of wavelength λ = 550 nm is used. The screen is placed L = 1.00 m from the slits. Calculate the fringe spacing β (distance between two consecutive bright fringes) on the screen. easy 1 mark Young's double‑slit fringe spacing
• 13 A diffraction grating has a line spacing of d = 1.2 μm. Two closely spaced spectral lines of wavelengths λ_1 = 500 nm and λ_2 = 502 nm are to be resolved in the third order (m=3) using Rayleigh’s criterion. Find the minimum total number of illuminated slits N that the grating must have. Show all steps clearly. hard 5 marks Resolving power of a diffraction grating (Rayleigh criterion)
• 14 A diffraction grating has 1200 lines per millimetre. Monochromatic light of wavelength λ = 650 nm falls normally on the grating. Calculate the angle θ (in degrees) at which the third order (m=3) maximum is observed. medium 2 marks Diffraction grating angular position
• 15 In a Young’s double‑slit experiment the slit separation is d = 0.25 mm and monochromatic light of wavelength λ = 480 nm is used. The screen is placed L = 1.5 m from the slits. Calculate the fringe spacing β (distance between two consecutive bright fringes) on the screen. easy 1 mark Young's double‑slit interference
• 16 A single slit of width a = 0.03 mm is illuminated by monochromatic light of wavelength λ = 550 nm. Find the smallest angle θ (in degrees) at which a minimum in the diffraction pattern occurs. medium MCQ 2 marks Single‑slit diffraction minima
• 17 Two spectral lines of wavelengths λ_1=620 nm and λ_2=623 nm are to be resolved using the second order (m=2) spectrum of a diffraction grating whose line spacing is d = 1.0 μm. Using Rayleigh’s criterion, find the minimum total number of illuminated slits N that the grating must have. hard 4 marks Resolving power of diffraction grating
• 18 A single slit of width 0.05,mm is illuminated by monochromatic light of wavelength 700,nm. The screen is placed 3.0,m behind the slit. Determine the linear width w of the central bright fringe on the screen. hard 5 marks Single‑slit central maximum width
• 19 Two spectral lines of wavelengths 590,nm and 594,nm are to be resolved using the fifth order (m=5) spectrum of a diffraction grating whose line spacing is 0.9,μm. Using Rayleigh’s criterion, what is the minimum total number of illuminated slits N required? hard MCQ 5 marks Grating resolving power
• 20 In a Young’s double‑slit experiment, the slit separation is 0.30,mm and monochromatic light of wavelength 550,nm is used. The screen is placed 2.0,m from the slits. Calculate the fringe spacing β (distance between two consecutive bright fringes) on the screen. medium 3 marks Young’s fringe spacing
• 21 A monochromatic light of wavelength 480,nm falls normally on a diffraction grating with line spacing 1.5,μm. Find the angle θ (in degrees) at which the second order (m=2) maximum is observed. easy 4 marks Grating angular positions
• 22 A single slit of width 0.04,mm is illuminated by monochromatic light of wavelength 600,nm. A screen is placed 2.0,m behind the slit. Determine the linear width of the central bright fringe on the screen. easy 2 marks Diffraction by single slit
• 23 In a Young’s double‑slit experiment the slit separation is 0.30,mm, the wavelength of light used is 550,nm, and the screen is placed 2.0,m from the slits. What is the fringe spacing on the screen? easy MCQ 2 marks Young’s double‑slit interference
• 24 Two spectral lines at wavelengths 590,nm and 594,nm are to be resolved using the fourth order (m=4) spectrum of a diffraction grating whose line spacing is 1.0,μm. Using Rayleigh’s criterion, find the minimum total number of illuminated slits N required. hard 4 marks Resolving power of a grating
• 25 A diffraction grating has 1250 lines per millimetre. Monochromatic light of wavelength 650,nm falls normally on the grating. Find the angle at which the first order (m=1) maximum is observed. medium 3 marks Diffraction by a grating
• 26 Two closely spaced spectral lines of wavelengths λ_1=480 nm and λ_2=485 nm are to be resolved using the fourth order (m=4) spectrum of a diffraction grating whose line spacing is d=1.0 μm. Using Rayleigh's criterion, determine the minimum total number of illuminated slits N that the grating must have. hard 5 marks Resolving power of diffraction grating (Rayleigh criterion)
• 27 In a Young's double‑slit experiment the slit separation is d=0.25 mm, the wavelength of the light is λ=600 nm and the screen is placed L=1.5 m from the slits. Calculate the distance β between two successive bright fringes on the screen. easy 1 mark Young's double‑slit fringe spacing
• 28 A diffraction grating has 1500lines per millimetre. Monochromatic light of wavelength λ=550 nm falls normally on the grating. (a) Find the angles θ_1 and θ_2 (in degrees) at which the first (m=1) and second (m=2) order principal maxima appear. (b) If a screen is placed D=2.0 m behind the grating, calculate the linear separation s between the two first‑order maxima on the screen. hard 5 marks Diffraction grating angular positions and linear separation
• 29 A Young’s double‑slit experiment is performed with a slit separation of 0.20,mm, a light of wavelength 520,nm, and the screen is 1.20,m away. What is the fringe spacing β between consecutive bright fringes? easy MCQ 1 mark Young’s double‑slit fringe spacing
• 30 A single slit of width 0.05,mm is illuminated by monochromatic light of wavelength 650,nm and a screen is placed 2.50,m behind the slit. What is the linear width of the central bright fringe on the screen? medium MCQ 2 marks Single‑slit diffraction central width
• 31 Two spectral lines at wavelengths 580,nm and 590,nm are to be resolved in the fourth order (m=4) spectrum of a diffraction grating whose line spacing is 1.20,μm. Using Rayleigh’s criterion, what is the minimum total number of illuminated slits N required? hard MCQ 4 marks Resolving power of diffraction grating
• 32 A diffraction grating has 500 lines per millimetre and is illuminated by monochromatic light of wavelength 550,nm. What is the angle θ (in degrees) at which the third order (m=3) maximum is observed? hard MCQ 4 marks Grating diffraction angle
• 33 A single slit of width a = 0.06 mm is illuminated by monochromatic light of wavelength λ = 550 nm. Find the angle θ (in degrees) of the first minimum in the diffraction pattern. easy 1 mark Single‑slit diffraction minima
• 34 In a Young’s double‑slit experiment the slit separation is d = 0.25 mm, the wavelength of light is λ = 600 nm and the screen is placed L = 1.8 m from the slits. (a) Find the fringe spacing β between adjacent bright fringes on the screen. (b) What is the distance from the central maximum to the 12th bright fringe? medium 2 marks Fringe spacing in double‑slit experiment
• 35 A diffraction grating has 1200 lines per centimetre and is illuminated by monochromatic light of wavelength λ=500 nm. (a) Find the angle θ (in degrees) at which the third order (m=3) maximum is observed. (b) A screen is placed D=4 m behind the grating. What is the linear separation s between the two third‑order maxima on the screen? (c) Which of the following choices gives the correct value of s? hard MCQ 3 marks Grating diffraction angle and image separation