An object is placed 40 cm from a concave mirror of focal length 20 cm. The image formed is

(b) – 20 cm is the correct option.

(d) When an object is placed between the pole and principal focus of a concave mirror, the image formed is virtual, erect, and larger than the object.

Here, in case of concave mirror u=10 cm [u, is always negative] v =?;m = - 3 [real image] Now the magnification formula is m= -v/u or -3= -(v/-10) or , v = -30 cm. Image will...

The image formed by a concave mirror is virtual, erect and larger only when the object is placed between the pole of the mirror and its principal focus. So correct...

Given, u=-10 cm, f=+15 cm,v=? From mirror formula, 1/f=1/v+1/u or 1/v=1/f=1/u =1/v=1/15=1/(-10)=1/15+1/10=(2+3)/30 or  v=30/5=+6 cm That is image is formed at a distance of 6 cm from the mirror behind it. The image is erect...

At infinity.

(c) both concave mirror and convex lens.

(d) 15 cm behind the mirror. EXPLANATION:  The option can be selected by suitable reasoning. In a convex mirror, the object at infinity has its image at the focus behind the mirror....

Case 1: When image is real v/u=-2x/x=-2 v= -2u 1/v+1/u=1/f=1/20 => 1/u-1/2u=1/20 =>1/2u=1/20 =>u=10 cm

(a) Virtual image formed is larger in size in case of concave mirror.