In which type of mirror does an object's tip appear to touch its image when in contact with the glass?

In which type of mirror does an object's tip appear to touch its image when in contact with the glass?

• A. Concave mirror
• B. Convex mirror
• C. Front surface mirror
• D. Plane mirror

Answer: (C)

The key idea is where the reflecting layer sits. In a front-surface mirror, the reflective coating is on the outermost surface, so light reflects right at the glass surface and the image forms essentially at that surface. That makes the image appear to lie exactly at the point where the object touches the glass, so the tip seems to touch its image when in contact. In mirrors where the reflection comes from the back of the glass, light travels through the glass, reflects, and then travels back out, which places the image a short distance behind the surface. In that case, touching the glass doesn’t produce a touching image. So the type of mirror that makes the tip appear to touch its image when in contact with the glass is a front-surface mirror.

The key idea is where the reflecting layer sits. In a front-surface mirror, the reflective coating is on the outermost surface, so light reflects right at the glass surface and the image forms essentially at that surface. That makes the image appear to lie exactly at the point where the object touches the glass, so the tip seems to touch its image when in contact.

In mirrors where the reflection comes from the back of the glass, light travels through the glass, reflects, and then travels back out, which places the image a short distance behind the surface. In that case, touching the glass doesn’t produce a touching image.

So the type of mirror that makes the tip appear to touch its image when in contact with the glass is a front-surface mirror.