Light and Shadow (Class 5 CBSE): quick revision, 15 bites

Light Makes Sight Possible

No light, no sight — that simple.

We see an object only when **light from it reaches our eyes** — either the object gives out light itself, or it reflects light from another source.

Takeaway. Without light, nothing is visible — light is what carries the image of an object to our eyes.

Luminous vs Non-Luminous Objects

Some objects shine, others just reflect.

Takeaway. Luminous objects emit light; non-luminous objects are visible only by reflected light.

Light Travels in Straight Lines

Light never bends around corners.

Light always travels in **straight lines**. This is why we cannot see around a corner and why shadows have sharp edges.

Takeaway. Straight-line travel of light is the reason shadows form directly behind objects.

How a Shadow Is Formed

Block the light, get a shadow.

The dark patch is the **shadow** — it forms only when light is blocked by an **opaque** object.

Takeaway. Shadow = light source + opaque object + screen, all in a straight line.

Transparent, Translucent, Opaque

Can you see through it? That's the test.

Takeaway. Only opaque objects cast strong shadows; transparent objects cast almost none.

Shadow vs Reflection

Dark patch or mirror image?

Takeaway. A shadow is a dark outline; a reflection is a detailed image — don't mix them up.

Shadows Are Not Reflections

A shadow has no colour — remember that.

Takeaway. Shadow = dark outline; reflection = coloured, detailed image.

Shadow Size Depends on Distance

Move closer, shadow grows.

Takeaway. Distance between object and light source controls the shadow's size.

Shadows Around Us

Shadows are everywhere — spot them.

Takeaway. Shadows are a daily, visible proof that light travels in straight lines.

Why Shadows Are Useful

Shadows do real jobs too.

Takeaway. Shadows are not just dark patches — they help us tell time, tell stories, and stay cool.

Remember the Three 'T-O-O' Words

Three words, one quick trick.

**T**ransparent → **T**hrough (see clearly) · **T**ranslucent → **T**hick-ish (see partly) · **O**paque → **O**ff (no light passes)

Takeaway. T-Through, T-Thick-ish, O-Off — quick way to recall the three types.

Exam Answer Checklist

Three points, full marks.

Takeaway. Mentioning the three requirements and 'straight-line travel' earns full marks.

Shadows on the Moon

Even the Moon casts shadows.

Astronauts on the Moon cast **very dark, sharp shadows** because there is no air there to scatter light into the shadow region.

Takeaway. Sharp shadows on the Moon show that air is what softens shadows on Earth.

Two Shadows, One Object

Two lights, two shadows.

If you shine **two torches** on one object from different sides, you get **two shadows** — one from each light source.

Takeaway. Each light source creates its own shadow — more lights, more shadows.

Predict the Shadow

Think before you answer.

Takeaway. Tracing a straight line from light through object to screen always predicts the shadow's position.