Ram, a science student, is trying to find the nature of a mirror he found in the lab. For doing that, he has set up an experiment. He kept a candle in front of a mirror and a screen behind the candle. Then, he started moving the screen until he got a clear image of the candle on the screen. Once the image is obtained, he measures and makes a note of the distances between the mirror, candle, and the screen as shown.
Ram can use this mirror as a: