For a plane mirror, \(h_{\mathrm{I}} = h_{\mathrm{O}}\), so the magnification is \(m =1\). For an optical device that results in magnification greater than 1, the image is larger than the object. Such a device is commonly called a magnifier; it forms a magnified image of the object. When \(m\) is less than one, the image formed by the optical device is smaller than the object. As we’ll see in later sections, a curved mirror can form an image that is either larger or smaller than an object placed in front of it.