Ray Optics

Assertion : A double convex lens $(\mu=1.5)$ has focal length $10 \mathrm{~cm}$. When the lens is immersed in water $(\mu=4 / 3)$, its focal length becomes $40 \mathrm{~cm}$. Reason :…

A bi-convex lens is formed with two thin plano-convex lenses as shown in the figure. Refractive index $n$ of the first lens is 1.5 and that of the second lens is 1.2. Both the curved surfaces are of the same radius of…

The refractive index of the material of an equilateral prism is 1.6. The angle of minimum deviation due to the prism would be

A telescope, whose objective lens has an aperture of $1 \mathrm{~mm}$ for the wavelength of light $500 Å$, then limiting resolving power of the telescope is

A spherical mirror forms an image of magnification 3. The object distance, if focal length of mirror is $24 \mathrm{~cm}$, may be

A fish in water (refractive index $n$) looks at a bird vertically above in the air. If $y$ is the height of the bird and $x$ is the depth of the fish from the surface, then the distance of the bird as estimated by the…

If focal length of human eye is $2 \mathrm{~cm}$, then find the focal length of contact lens, such that a combined focus system of focal length $2.5 \mathrm{~cm}$ is obtained after using contact lens.

Focal length of convex lens is $100 \mathrm{~cm}$ and focal length of concave lens is $8 \mathrm{~cm}$. Find the magnification of the given combination of lens if object is placed at point $O$.

Assertion : Rainy clouds appear dark from below. Reason : There is not sufficient light which can be scattered by these clouds.

In a simple microscope of focal length $5 \mathrm{~cm}$, final image is formed at the least distance of distinct vision, then its magnification will be

Assertion : A ray of light is incident from outside on a glass sphere surrounded by air. This ray may suffer total internal reflection at second interface. Reason : If a ray of light goes from denser to rarer medium, it…

The least distance of vision of a longsighted person is $60 \mathrm{~cm}$. By using a spectacle lens, this distance is reduced to $12 \mathrm{~cm}$. The power of the lens is