Ray Optics

The magnifying power of a telescope is 9 . When it is adjusted for parallel rays, the distance between the objective and eyepiece is 20 cm . The ratio of focal length of objective lens to focal length of eyepiece is…

Power of biconvex lens is $P$ diopter. When it is cut into two symmetrical halves by a plane containing the principal axis. The ratio of power of two halves is

In normal adjustment, for a refracting telescope, the distance between objective and eye piece is 30 cm . The focal length of the objective, when the angular magnification of the telescope is 2 , will be:

A thin prism $P_1$ with an angle $6^{\circ}$ and made of glass of refractive index 1.54 is combined with another prism $\mathrm{P}_2$ made from glass of refractive index 1.72 to produce dispersion without average…

In a reflecting telescope, a secondary mirror is used to:

An achromatic convergent doublet of two lense in contact has a power of $+5 \mathrm{D}$. The power of converging lens is $+6 \mathrm{D}$. The ratio of the dispersive power of the convergent and divergent lenses is

Green light of wavelength $5460 Å$ is incident on an airglass interface. If the refractive index of glass is $1.5$, the wavelength of light in glass would be $\left(\mathrm{c}=3 \times 10^{8} \mathrm{~ms}^{-1}\right)$

A vessel of depth $2 \mathrm{~d} \mathrm{~cm}$ is half filled with a liquid of refractive index $\mu_{1}$ and the upper half with a liquid of refractive index $\mu_{2}$. The apparent depth of the vessel seen…

A convex lens of focal length $25 \text{cm}$ produces images of the same magnification $2$, when an object is kept at two positions ${x}_{1}$ and ${x}_{2}$ $({x}_{1}>{x}_{2})$ from the lens. The ratio of ${x}_{2}$ and…

The focal length of a thin convex lens for red and blue rays are $100 \text{cm}$ and $96\cdot 8 \text{cm}$ respectively. Then, the dispersive power of the material of the lens is

A lens having focal length $f$ and aperture of diameter $d$ forms an image of intensity $I$. Aperture of diameter $\frac{d}{2}$ in central region of lens is covered by a black paper. Focal length of lens and intensity…

A biconvex lens has a radius of curvature of magnitude $20 \mathrm{~cm}$. Which one of the following options best describe the image formed of an object of height $2 \mathrm{~cm}$ placed $30 \mathrm{~cm}$ from the lens?