Mirror equation

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1. Mirror Equation Subtitle

2. Mirror Equation There is an important relationship between the distance of an object , distance of an image , and the focal length of the spherical mirror. This relationship is known as the mirror equation. The mirror equation expresses the quantitative relationship between the object distance (d o ), the image distance (d i ), and the focal length (f). In symbols, = +  

3. This mirror equation is both applicable to concave and convex mirrors . In a concave mirror , the focal length is positive (+) while in a convex mirror it is negative (-) . The distance of the object and the distance of the image is taken as positive (+) because they are both located in front of the mirror and taken as negative (-) for virtual images because they are formed behind the mirror.

4. Example 1: A flower vase is placed 15 cm in front of a concave mirror whose focal length is 10 cm. Where is the image of the flower vase located? Describe the image formed. Given: d o = 15 cm f = 10 cm Solution: Using the basic equation, derive the formula for the distance of the image.

5. = + f d o d i f d o d i d o d i = fd i + fd o d o d i – fd i = fd o = d i = d i = di = d i = d i = 30 cm