1. What is the reflection of light?
Answer: Reflection of light is the bouncing back of light rays from a surface when they strike it.
2. Explain spherical mirrors and the mirror formula.
Answer: Spherical mirrors are mirrors whose reflecting surface is a part of a sphere. The mirror formula,
relates the focal length (f), object distance (u), and image distance (v) of a spherical mirror.
3. Describe the refraction of light at plane and spherical surfaces.
Answer: Refraction of light is the bending of light rays as they pass from one medium to another. At plane surfaces, refraction obeys Snell’s law. Spherical surfaces follow the same principles, but with different geometric shapes.
4. What are the thin lens formula and lens maker formula?
Answer: The thin lens formula,
relates the focal length (f), object distance (u), and image distance (v) of a lens. The lens maker formula calculates the focal length of a lens based on its refractive index and radii of curvature.
5. Explain total internal reflection and its applications.
Answer: Total internal reflection occurs when light traveling from a denser to a rarer medium is incident at an angle greater than the critical angle. Its applications include fiber optics, mirages, and optical prisms.
6. Define magnification and its significance.
Answer: Magnification is the ratio of the height of an image to the height of the object. It indicates how much larger or smaller an image appears compared to the object.
7. What is the power of a lens?
Answer: The power of a lens is the reciprocal of its focal length and is measured in diopters (D). It indicates the ability of the lens to converge or diverge light.
8. How are thin lenses combined in contact?
Answer: Thin lenses in contact are combined by adding their individual powers to get the total power of the combination.
9. Explain the refraction of light through a prism.
Answer: When light enters a prism, it undergoes refraction and disperses into its component colors due to the different wavelengths of light bending by different amounts.
10. Describe the microscope and its magnifying power.
Answer: A microscope is an optical instrument used to magnify small objects. Its magnifying power is the ratio of the apparent size of the object seen through the microscope to the actual size of the object.
11. Discuss the astronomical telescope and its magnifying power.
Answer: An astronomical telescope is used for viewing distant objects such as stars and planets. Its magnifying power is the ratio of the focal length of the objective lens to the focal length of the eyepiece.
12. Explain wavefront and Huygens’ principle.
Answer: A wavefront is an imaginary surface that connects all points of a wave that are in the same phase. Huygens’ principle states that every point on a wavefront can be considered as a source of secondary spherical wavelets that spread out in all directions.
13. How are laws of reflection and refraction explained using Huygens’ principle?
Answer: According to Huygens’ principle, the laws of reflection can be explained by assuming that each point on a wavefront acts as a new source of waves. Refraction can be explained by considering how wavefronts change direction as they pass from one medium to another.
14. Discuss interference and Young’s double-slit experiment.
Answer: Interference is the phenomenon of two or more waves overlapping to produce a resultant wave of greater, lower, or the same amplitude. Young’s double-slit experiment demonstrates interference patterns produced by light passing through two closely spaced slits.
15. What is the expression for fringe width in Young’s double-slit experiment?
Answer: The expression for fringe width (w) in Young’s double-slit experiment is given by
, where λ is the wavelength of light, D is the distance between the slits and the screen, and d is the separation between the slits.
16. Define coherent sources and sustained interference of light.
Answer: Coherent sources are sources of light that emit waves with a constant phase difference. Sustained interference occurs when the phase difference between waves remains constant over time, resulting in a stable interference pattern.
17. Explain diffraction due to a single slit and the width of the central maximum.
Answer: Diffraction due to a single slit is the bending of light waves as they pass through a narrow aperture. The width of the central maximum in the diffraction pattern depends on the width of the slit and the wavelength of light.
18. What is polarization and plane-polarized light?
Answer: Polarization is the phenomenon in which light waves vibrate in a particular plane perpendicular to the direction of propagation. Plane-polarized light consists of waves vibrating in a single plane.
19. Discuss Brewster’s law and the uses of plane-polarized light.
Answer: Brewster’s law states that the angle of incidence at which light becomes completely polarized upon reflection from a surface is equal to the angle whose tangent is the refractive index of the second medium. Plane-polarized light is used in various applications including glare reduction and in certain types of 3D glasses.
20. Explain Polaroid and its significance.
Answer: Polaroid is a type of polarizing material that selectively absorbs light waves vibrating in certain planes, allowing only light waves vibrating in a particular plane to pass through. It’s used in photography, sunglasses, LCD screens, and other optical devices.