Which of the following can produce a magnification of $+5$ as well as $-5$?

At what distance should an object be placed to obtain its real,inverted and of same size image as the object by a convex lens?

When is the magnitude of the power of a lens equal to its focal length?

What is the point,where the rays parallel to the principal axis meet after reflection,called?

$A$ student wants to project the image of a candle flame on a screen $60\, cm$ in front of a mirror by keeping the flame at a distance of $15\, cm$ from its pole.
$(a)$ Write the type of mirror he should use.
$(b)$ Find the linear magnification of the image produced.
$(c)$ What is the distance between the object and its image?
$(d)$ Draw a ray diagram to show the image formation in this case.

$A$ convex mirror has a focal length $f$. $A$ real object is placed at a distance $f$ in front of it. The mirror produces an image at