A dentist's mirror has a radius of curvature of 3 cm. How far must it be placed from a small dental cavity to give a virtual image of the cavity that is magnified five times?
The dentist's mirror is a concave mirror.
Radius of curvature 'R' = -3 cm
focal length of the mirror `f=R/2=(-3)/2=-1.5 `cm
Given that magnification 'm' = 5
Therefore, using the magnification formula, we get `m=-v/u`
Now, using the mirror formula, we get
⇒ `u=-1.2 cm`
The dentist should place the object at a distanc of 1.2 cm from the mirror.
focal length of the mirror` f=R_2=32=1.5 cm`
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Solution A Dentist'S Mirror Has a Radius of Curvature of 3 Cm. How Far Must It Be Placed from a Small Dental Cavity to Give a Virtual Image of the Cavity that is Magnified Five Times? Concept: Mirror Formula and Magnification.