Two lenses with powers +12D and -2D are kept in close contact with each other. Find the power and the focal length of the combination.

If two lenses of focal lengths f_(1) and f_(2) are kept in contact with each other, state the formula for the focal length of the combination . If P_(1) and P_(2) are the powers of these lenses, state the formula for the power of the combination.

Two lenses of powers, 15D and +5D are in contact with each other forming a combination lens. What is the focal length of the combination?

Answer the following questions : If two lenses of focal length f_1 and f_2 are kept in contact with each other , state the formula for the focal length of the combination . If p_1 and P_2 are the power of these lenses, state the formula for the power of the combination .

If two lenses of power 2D and 3D are kept in contact with each other, then focal length of the combination will be .......... cm.

Two thin lenses having optical powers of -10 D and + 6 D are placed in contact with each other. The focal length of the combination is :

Two lenses of power + 15 D and - 5 D are in contact with each other. What is the focal length of the combination ? What would be the position of image formed by the combination for an object at 30 cm ?

Two thin converging lenses of focal lenths 15 cm and 30 cm are held in contact with each other.Calculate power and focal length of the combination.

Two lenses of power +15 D and -5 D are in contact with each other forming a comvination lens. what is the focal length of this combination?

Two lenses of focal lengths 0.20 m and 0.30 m are kept in contact with each other. Calculate the resultant focal length of the combination. Also calculate the powers of the individual lenses and that of the equivalent lens.