$A$ concave mirror of focal length $f$ produces a real image $n$ times the size of the object. The magnitude of the distance of the object from the mirror is:

While using an electric bulb for street lighting, the reflector should be a:

The image formed by a convex mirror of focal length $30 \ cm$ is a quarter of the size of the object. The distance of the object from the mirror is......$cm$

What will be the height of the image (in $mm$) when an object of $2 \, mm$ is placed on the axis of a convex mirror at a distance of $20 \, cm$,given the radius of curvature is $40 \, cm$?

An object is placed at $20 \, cm$ from a convex mirror of focal length $10 \, cm$. The image formed by the mirror is

In an experiment to determine the focal length $(f)$ of a concave mirror by the parallax method,a student places the object pin $\text{A}$ on the principal axis at a distance $x$ from the pole $\text{P}$. The student looks at the pin and its inverted image from a distance,keeping his/her eye in line with $\text{PA}$. When the student shifts his/her eye towards the left,the image appears to the right of the pin. Then: