NCERT Solutions for Class 7th Science Chapter 11 .5 Reflection of Light — Activity 11.5: Let us investigate

Book page 159 & 16011 Updated on2026-09-19

Q1.

Take it outside and let the sunlight fall on the shiny surface. What can you do to redirect light on the wall on which the sunlight is not falling directly?

Answer

Hold the plane mirror (or the shiny steel plate) in the sunlight and slowly turn and tilt it until the patch of light it throws lands on the shaded wall.

Sunlight falling on the mirror is reflected. By changing the way the mirror faces, you change the direction in which the reflected light goes — so you can steer that bright patch on to a wall which the Sun itself cannot reach.

Caution: Never direct the reflected sunlight into anyone's eyes.

Q2.

Turn the shiny plate or mirror in different directions to redirect the light onto a wall or a nearby surface (Fig. 11.8). Do you see a spot of light on the wall? Does it mean that the shiny plate or mirror has changed the direction of light?

Fig. 11.8, page 160 (redrawn sketch): a shiny plate or mirror turns sunlight onto a shaded wall, where a bright spot appears.

Answer

Yes — a bright spot of light appears on the wall, and yes, it does mean that the mirror has changed the direction of the light.

Why it happens: Sunlight comes down to the mirror along one straight line. It cannot reach the shaded wall by itself, because nothing bends it. When it strikes the polished surface, it is turned away along a new straight line, and that new line ends on the wall. The bright spot is proof that the light has been reflected — sent back in a different direction.

Q3.

Now, tilt the shiny plate or mirror in different ways and observe the light spot on the wall. Does it change position?

Answer

Yes. Each time the mirror is tilted, the bright spot jumps to a new place on the wall. A small tilt of the mirror moves the spot a long way.

Why it happens: The direction of the reflected light depends on how the mirror is turned. Tilt the mirror and the reflected ray swings round with it, so the spot shifts. Between the mirror and the wall, though, the light still travels perfectly straight — light always travels in straight lines and changes direction only where it meets the mirror.

Conclusion of the activity: A shiny surface or a mirror changes the direction of the light that falls on it. This change in direction of light by a mirror is called the reflection of light.

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