Question

Where must you place an object in front of a concave mirror with radius Rso that the image is erect and times the size of the object? Where is the image?

Short answer

The object must be placed at 0.3R in front of a concave mirror and the image must be placed at 0.75R.

Step-by-step solution

Determine the position of the object and the image

The radius is in the direction of the outgoing rays, thus, R is positive, also, the image is erect.

Use the formula of lateral magnification for a spherical mirror

Substituting the values

So, the position of the image

Therefore, the object must be placed at 0.3R in front of a concave mirror and the image must be placed at 0.75R.