Optics
Topics
- Reflection, spherical mirrors, mirror formula
- Refraction at plane and spherical surfaces, thin lens and lens maker formula
- Total internal reflection and applications
- Magnification, power of lens, combination of thin lenses
- Refraction through a prism
- Microscope and astronomical telescope
- Interference and Young's double-slit experiment
- Diffraction due to a single slit
- Polarization, Brewster's law, Polaroids
Chapter tests
See all →Top questions
See all →- The intensity of transmitted light when a polaroid sheet, placed between two crossed polaroids at 22.5^° from the polarization axis of one of the polaroid, is (I_0 is the intensity of polarised light after passing through the first polaroid): Answer: 3. I₀/8 Key idea: apply Malus's law, I=I₀cos²θ , at each polaroid. The middle sheet is at 22.5^° to the first, and 90^°-22.5^°=67.5^... 1
- An unpolarized light beam travelling in air is incident on a medium of refractive index 1.73 at Brewster's angle. Then- Answer: 1. reflected light is completely polarized and the angle of reflection is close to 60^° Key idea: at Brewster's angle tan i_B=μ , an... 1
- In a certain camera, a combination of four similar thin convex lenses are arranged axially in contact. Then the power of the combination and the total magnification in comparison to the power (p) and magnification (m) for each lens will be, respectiv… Answer: 3. 4p and m⁴ Key idea: powers of thin lenses in contact add, while magnifications of successive images multiply. Power: P=p+p+p+p=4p... 1
- A microscope has an objective of focal length 2 cm, eyepiece of focal length 4 cm and the tube length of 40 cm. If the distance of distinct vision of eye is 25 cm, the magnification in the microscope is Answer: 2. 125 Key idea: for a compound microscope, the magnification is the product of the objective magnification and the eyepiece magnifi... 1
- A small telescope has an objective of focal length 140 cm and an eye piece of focal length 5.0 cm. The magnifying power of telescope for viewing a distant object is: Answer: 3. 28 Key idea: For a telescope in normal adjustment (distant object), m=f_o/f_e . m=140/5.0=28 . Option 3. 1
- If the monochromatic source in Young's double slit experiment is replaced by white light, then Answer: 4. there will be a central bright white fringe surrounded by a few coloured fringes. Key idea: Each colour makes its own fringe patt... 1