$A$ small rod of length $2 \, mm$ lies along the principal axis at a distance of $30 \, cm$ from a concave mirror of focal length $20 \, cm$. The axial length of the image of the rod is.....$mm$.

For a concave mirror,the minimum distance between a real object and its real image is ...........

Define the focal plane of a concave mirror.

$A$ mobile phone lies along the principal axis of a concave mirror,as shown in the figure. Show by a suitable diagram,the formation of its image. Explain why the magnification is not uniform. Will the distortion of the image depend on the location of the phone with respect to the mirror?

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:

The field of view is maximum for