An object is placed in front of a convex lens of focal length $11\text{cm}$. If the image formed is virtual and has a magnification of $2$, the distance of the object from the lens is -

Q. A small object is so placed in front of a convex lens of 5 cm focal length that a virtual image is formed at a distance of 25 cm. Find the magnification.

Q. The magnification of an object placed in front of a convex lens of focal length $20cm$ is $+2$. The image distance is________.

Q.

Complete the following sentences :

(a) An object is placed at a distance of more than 40 cm from a convex lens of focal length 20 cm. The image formed is real, inverted and ..........

(b) An object is placed at a distance 2f from a convex of lens of focal length f. The size of image formed is ............ that of the object.

(c) An object is placed at a distance 5 cm from a convex of focal length 10 cm. The image formed is virtual, upright and ............

Q. The magnification of an object placed in front of a convex lens is $+2$. The focal length of the lens is $2.0$ metres. Find the distance by which object has to be moved to obtain a magnification of $-2$ (in cm).

Q. The magnification of an object placed in front of a convex lens of focal length $20cm$ is $+2$. To obtain a magnification of $-2$, the object has to be moved a distance equal to: