Shadows

• A shadow forms when an opaque object blocks light and stops it from passing through.
• Opaque objects (like wood or metal) block light completely; transparent objects (like clear glass) let light pass through easily and form no dark shadow.
• Translucent objects (like butter paper or frosted glass) let only some light pass through, forming a faint, blurry shadow.
• A shadow forms on the side of the object away from the light source, on a screen or the ground.
• The size of a shadow changes with the distance of the light source — moving the light closer to the object makes the shadow bigger.

Level 1 - Core idea

Verbal: A shadow forms when an opaque object blocks light, appearing on the surface behind the object, away from the light source. Moving the light source closer to the object makes its shadow larger.

Symbolic: opaque object + light source -> dark shadow behind the object; light closer to object -> bigger shadow

Visual: Hold your hand close to a torch pointed at a wall — the shadow of your hand grows huge as you bring the torch nearer.

Level 2 - NCERT anchor

NCERT Looking Around 5 connects this to daily observation of shadows changing length through the day, from morning to noon to evening.

At noon, when the Sun is almost overhead, why does your shadow look short?

Step 1 - At noon the Sun is high up, almost directly above.
Step 2 - Light travels almost straight down onto you.
Step 3 - Your shadow falls almost directly under your feet, making it short.
Answer: The shadow is short at noon because the Sun is high overhead.

You hold a sheet of clear glass and a piece of wood in front of a lamp. Which one forms a dark shadow, and why?

Step 1 - Clear glass is transparent and lets light pass through easily.
Step 2 - Wood is opaque and blocks light completely.
Step 3 - Blocking light is what creates a dark shadow.
Answer: The wood forms a dark shadow; the glass does not because it is transparent.

• What kind of object is needed to form a dark shadow?
• Why does a glass window not form a dark shadow?
• On which side of an object does its shadow appear?
• What happens to a shadow's size when the light source moves closer?
• Stretch: Why is your shadow long in the early morning but short at noon?

Revision tip: Use a torch and a toy at home to watch how the shadow changes as you move the torch closer and farther.

Open the Practice tab for graded questions on Shadows.