Embibe Experts Solutions for Exercise 4: Assignment

Which of the following is incorrect?

A double concave thin lens made out of glass $\left(\mathrm{\mu }=1.5\right)$ have radii of curvature $500\mathrm{cm}$. This lens is used to rectify the defect in vision of a person. The far point of the person will be at

A convex lens forms a real image $16\mathrm{mm}$ long on a screen. If the lens is shifted to a new position without disturbing the object or the screen then again a real image of length $81\mathrm{mm}$ is formed. The length of the object must be

A point object is moving with speed $u_0$ at a position somewhere between $2F$ and $F$ in front of a convex lens. The speed of its image is

An object is placed in front of two convex lenses one by one at a distance $u$ from the lens. The focal lengths of the lenses are $30\mathrm{cm}$ and $15\mathrm{cm}$ respectively. If the size of image formed in the two cases is same, then $u$ is

If ${\mathrm{R}}_1$ and ${\mathrm{R}}_2$ are the radii of curvature of the spherical surfaces of a thin lens and ${\mathrm{R}}_1>{\mathrm{R}}_2$, then this lens can

The focal length of a thin lens in vacuum is $\mathrm{f}$. If the material of the lens has $\mathrm{\mu }=\frac{3}{2}$, its focal length when immersed in water of refractive index $\frac{4}{3}$ will be

For an astronomical telescope having ${\mathrm{f}}_{\mathrm{o}}$ as the focal length of the objective and ${\mathrm{f}}_{\mathrm{e}}$ as the focal length of the eyepiece, the length of the telescope tube in normal adjustment is