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A concave shaving mirror has a radius of curvature of 60 cm…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A concave shaving mirror has a radius of curvature of . A man holds his face from it. Use the New Cartesian sign convention. Find the image distance, with its sign, and the magnification. Say whether the image is real or virtual.
Need a reminder? The key ideaShow
For a spherical mirror in the New Cartesian convention, with , and the magnification is . A real object has . A concave mirror has , and a convex mirror has . A positive means a virtual image behind the mirror.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. , so . The object distance is .
Plan. We find from the mirror formula and then the magnification.
Step 1. The image distance. We want , so .
Step 2. The magnification. .
Answer: and . The positive means the image is virtual, behind the mirror. The positive means it is upright, and twice as large as the face.
Check. The face is inside the focal length (). A concave mirror gives a virtual, upright, larger image there. It agrees.
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