Reflection and Mirror Images
Class 7 Science · Chapter 11: Light: Shadows and Reflections · NCERT Curiosity section 11.5–11.6
Learn
Meher holds a shiny steel plate in the sunlight and a bright spot dances on the shaded wall. Tilting the plate moves the spot. A shiny surface or mirror changes the direction of light: this is reflection. With a comb slit making a thin beam on paper, she sees the beam bounce off a mirror in a new direction.
A pen in front of a plane mirror seems to have a twin behind it: its image. The image is the same size as the object, erect (upright), and as far behind the mirror as the object is in front. It cannot be caught on a screen.
Ishaan raises his left hand; his image raises its right. This left–right swap is lateral inversion, which is why AMBULANCE is painted in mirror letters on the front of ambulances: drivers ahead read it correctly in their rear-view mirrors. Kerala's Aranmula Kannadi is a metal mirror still made by hand, as mirrors were long before glass.
Explore: draw the mirror image.
- The letter F stands in front of a mirror (the dashed line). Colour its image.
Remember
- Reflection is the change in direction of light at a mirror or shiny surface.
- A plane mirror's image is the same size, erect, as far behind as the object is in front, laterally inverted, and not on a screen.
Quick check
Which is NOT true of an image in a plane mirror?
- it can be caught on a screen
- it is erect
- it is the same size
- it is laterally inverted
Answer
it can be caught on a screen. A plane mirror's image appears behind the mirror and cannot form on a screen.
Think about it
Which capital letters would look exactly the same in a mirror, and why?
One answer
Letters like A, H, I, M, O, T, U, V, W, X, Y, because each has a vertical line of symmetry, so swapping left and right changes nothing.
Practice
Practise with fresh questions at three levels (easy, medium, hard), some answered hands-on, with hints and worked answers. Get 4 of your last 5 right to finish the topic.