Image : Real Image and virtual Image
Activity
Take a plane mirror, concave mirror, a candle and white screen. Place a candle between plane mirrors and white screen. Switch off the light in a room. Glow the candle by using matchbox. Adjust screen and plane mirror with candle. Now observe carefully, what will be your observation? There is no formation of image on screen.
Now replace plane mirror with concave mirror and do the same procedure again as it is and observe carefully. Inverted image is obtained on screen.
From this activity it is clear that, when image does not appear or formed on a screen is called virtual image and when image appears or formed on a screen is called as real image.