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.

Combination of lenses are used in optical instruments to obtain the required power. What do you mean by power of a lens ? Express its unit.

Combination of lenses are used in optical instruments to obtain the required power. Draw a neat schematic ray diagram for the foma tion of image due to a point object placed in front of two thin convex lenses placed in contact

Two lenses of focal lengths f_1 and f_2 , are placed in contact. Obtain a general expression for effective focal length in terms of f_1 and f_2

Two lenses L_1 and L_2 are placed in contact as shown in figures. The focal length of each lens is 10cm.What is effective focal length of combination

Resistance are used to reduce the current flow in a circuit. Resistance can be connected in series and parallel to obtain the required value of resistance. Derive an expression for the effective resistance when three resistors are connected in parallel.

Two convex lense are given in the figure A and figure B.Which has more power