$A$ $2.0 \,cm$ object is placed $15 \,cm$ in front of a concave mirror of focal length $10 \,cm$. What is the size and nature of the image?

$A$ 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.....$mm$.

All of the following statements are correct except (for a real object):

An object placed in front of a concave mirror at a distance of $x \ cm$ from the pole gives a $3$ times magnified real image. If it is moved to a distance of $(x+5) \ cm$, the magnification of the image becomes $2$. The focal length of the mirror is: (in $cm$)

$A$ concave mirror is used to form an image of the Sun on a white screen. If the lower half of the mirror were covered with an opaque card,the effect on the image on the screen would be

When an object is placed at a distance of $25 \; cm$ from a mirror,the magnification is $m_1$. The object is moved $15 \; cm$ away with respect to the earlier position,magnification becomes $m_2$. If $\frac{m_1}{m_2} = 4$,the focal length of the mirror is: (in $; cm$)