[" A concave lens of focal length "40cm" ,a concave lens of focal length "40cm" and a con "],[" this combination in dioptre is "]

A convex lens of focal length 30 cm and a concave lens of focal length 60 cm are placed in combination. If an object is placed 40 cm away from the combination, find the position of the image.

A convex lens of focal length 40 cm a concave lens of focal length 40 and a concave lens of focal length 15 cm are placed in contact. The power of this combination of are placed in contact. The power of this combination in diopters is

An eye specialist prescribes spectacles having combination of convex lens of focal length 40cm in contact with a concave lens of focal length 25cm. The power of this lens combination in diopters is

An eye specialist prescribes spectacles having combination of convex lens of focal length 40cm in contact with a concave lens of focal length 25cm. The power of this lens combination in diopters is

An eye specialist prescribes spectacles having combination of convex lens of focal length 40cm in contact with a concave lens of focal length 25cm. The power of this lens combination in diopters is

A thin convex lens of focal length 10 cm and a thin concave lens of focal length 20 cm are in contact. The combination acts as :

A convex lens of focal length 40cm is in contact with a concave lens of focal length 25cm. The power of the combination is

A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is

A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is

A convex lens of focal length 84 cm is in contact with a concave lens of focal length 12 cm . The power of combination (in diopters) is