[" nature,and magnification of the image in each case."],[" 5.Obtain the equivalent focal length of combination of thin lenses placed in contact."]

Obtain an expression for focal length of a combination of thin lenses in contact.

Derive the expression for the equivalent focal length of a combination of two thin convex lenses in contact.

Derive an expression for the equivalent focal length for two thin convex lenses in contact.

How do magnification and focal length change for a combination of thin lenses ?

Combination of lenses are used in optical instruments to obtain the required power. Obtain an expression for the effective focal length of the combination of two thin convex lenses in contact.

Deduce the equivalent focal length of two convex lenses of focal lengths F_(1) and F_(2) when placed in contact.