The image formed by a concave mirror is observed to be virtual,erect and larger than the object. Then the position of the object should be

How can you distinguish between a plane mirror,a convex mirror,and a concave mirror by merely looking at the image formed in each case?

Draw a labelled ray diagram to locate the image of an object formed by a convex lens of focal length $20 \, cm$ when the object is placed $30 \, cm$ away from the lens.

With the help of a ray diagram,show the formation of an image by a convex lens when the object is placed between $F$ and $2F$. Write two characteristics of the image so formed.

$(a)$ Define principal focus of a spherical mirror.
$(b)$ For what position of the object does a concave mirror form a real,inverted and diminished image of the object? Draw the ray diagram.
$(c)$ An object $4 \,cm$ high is placed at a distance of $6 \,cm$ in front of a concave mirror of focal length $12 \,cm$. Find the position of the image formed.

The image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens. If the image is three times the size of the flame and the distance between the lens and the image is $80 \, cm$,at what distance should the candle be placed from the lens? What is the nature of the image at a distance of $80 \, cm$ from the lens (in $, cm$)?