How is the focal length of a mirror measured?

The focal length of a mirror is measured by the distance between the mirror and its focal point.

To measure the focal length of a mirror, one can use the mirror formula, which relates the distance of the object from the mirror (u), the distance of the image from the mirror (v), and the focal length of the mirror (f). The formula is 1/f = 1/u + 1/v.

To use this formula, one can place an object at a known distance from the mirror and measure the distance of the image formed by the mirror. By substituting these values into the mirror formula, the focal length of the mirror can be calculated.

Another method to measure the focal length of a mirror is to use a collimated beam of light. A collimated beam of light is a beam of light that is parallel to the axis of the mirror. By measuring the distance between the mirror and the point where the collimated beam converges, the focal length of the mirror can be determined.

In addition, a concave mirror can be used to form a real image of a distant object. By measuring the distance between the mirror and the real image, the focal length of the mirror can be calculated using the mirror formula.

Overall, there are several methods to measure the focal length of a mirror, including using the mirror formula, a collimated beam of light, and a real image of a distant object.