A lens has a focal length of 28 cm and a diameter of 4.0 cm. What is the f - number of the lens?

An optician is designing a contact lens. The material has is an index of refraction of 1.45. In order to yield the prescribed focal length, the optician specifies the following dimensions: inner radius of curvature = +2.60 cm outer radius of curvature = +1.98 cm where the inner radius of curvature describes the surface that touches the eye, and the outer radius of curvature describes the surface that first interacts with incoming light. What is the focal length of this contact lens (in cm)?

An optician is designing a contact lens. The material has is an index of refraction of 1.35. In order to yield the prescribed focal length, the optician specifies the following dimensions: inner radius of curvature = +2.60 cm outer radius of curvature = +2.06 cm where the inner radius of curvature describes the surface that touches the eye, and the outer radius of curvature describes the surface that first interacts with incoming light. What is the focal length of this contact lens (in cm)? answer in cm

A plane convex lens is made of glass ( n = 1.5) with one flat surface and the other having a radius of 30 cm. What is the focal length (in cm) of the lens?

6. A convex (converging) lens has a focal length of 12.5 cm. Where on the lens axis should an object be placed in order to get a vwtual, enlarged image with a magnification of 2.50?

An object is placed 40 cm in front of a thin lens. If an image forms at a distance 120 cm from the lens, on the same side as the object, what is the focal length of the lens, in cm? Your answer needs to have 2 significant figures, including the negative sign in your answer if needed. Do not include the positive sign if the answer is positive. No unit is needed in your answer, it is already given in the question statement.

The distance between the objective and eyepiece lenses in a microscope is 21 cm . The objective lens has a focal length of 5.0 mm .   What eyepiece focal length will give the microscope an overall angular magnification of 350?

A camera lens used for taking close-up photographs has a focal length of 25.0 mm. The farthest it can be placed from the film is 30.0 mm. (a) What is the closest object (in mm) that can be photographed? ANS: ___ mm   What is the magnification of this closest object? ANS: _____ X

a converging lens has a focal length of 4.5cm. it forms an inverted image with an image distance of 5.5cm what is the magnification?

An optician is designing a contact lens. The material has is an index of refraction of 1.30. In order to yield the prescribed focal length, the optician specifies the following dimensions: inner radius of curvature = +2.46 cm outer radius of curvature = +2.02 cm where the inner radius of curvature describes the surface that touches the eye, and the outer radius of curvature describes the surface that first interacts with incoming light. What is the focal length of this contact lens (in cm)?