Write uses of shperical mirrors

Write uses of herbarium.

Write uses of cotton.

Write use of freons?

Write two uses of ethers.

Write one use of echo.

Write two uses of ethers.

An object is plced at a distance of 25 cm from a shperical mierror and its image is formed behind the mirror at a distance of 5 cm.Find the focal length of the mirror.Is the mirror concave or convex in nature?