List the materials of the objects in Table 11.1 and classify them into transparent, translucent, and opaque. Table 11.1: Light through different materials Material Transparent / Translucent / Opaque Light will pass fully / partially / not at all My prediction My observation Cardboard &

Here is Table 11.1 completed. The last two rows are objects you may add from your own classroom. Material Transparent / Translucent / Opaque Light will pass fully / partially / not at all My prediction My observation Cardboard Opaque Not at all Not at all Paper Translucent (thin paper) / Opaque (thick paper) Partially Partially — a dim glow is seen through thin paper Glass (clear window glass) Transparent Fully Fully — the bright spot stays on the screen Tracing paper Translucent Partially Partially — a blurred patch of light Thick cloth Opaque Not at all Not at all Polythene sheet (thin, colourless) Transparent to translucent Fully Almost fully; slightly hazy Steel plate / wooden scale Opaque Not at all Not at all Tip: Judge a material by how clearly you can see through it — sharp view = transparent, blurred glow = translucent, nothing at all = opaque.

NCERT Solutions for Class 7th Science Chapter 11 .3 Light through Transparent, Translucent, and Opaque Materials — Activity 11.3: Let us experiment

Book page 156 & 15711 Updated on2026-09-19

Q1.

List the materials of the objects in Table 11.1 and classify them into transparent, translucent, and opaque.

Table 11.1: Light through different materials

Material	Transparent / Translucent / Opaque	Light will pass fully / partially / not at all
Material	Transparent / Translucent / Opaque	My prediction	My observation
Cardboard
Paper
Glass
Tracing paper
Thick cloth
…
…

Answer

Here is Table 11.1 completed. The last two rows are objects you may add from your own classroom.

Material	Transparent / Translucent / Opaque	Light will pass fully / partially / not at all
Material	Transparent / Translucent / Opaque	My prediction	My observation
Cardboard	Opaque	Not at all	Not at all
Paper	Translucent (thin paper) / Opaque (thick paper)	Partially	Partially — a dim glow is seen through thin paper
Glass (clear window glass)	Transparent	Fully	Fully — the bright spot stays on the screen
Tracing paper	Translucent	Partially	Partially — a blurred patch of light
Thick cloth	Opaque	Not at all	Not at all
Polythene sheet (thin, colourless)	Transparent to translucent	Fully	Almost fully; slightly hazy
Steel plate / wooden scale	Opaque	Not at all	Not at all

Tip: Judge a material by how clearly you can see through it — sharp view = transparent, blurred glow = translucent, nothing at all = opaque.

Q2.

Predict what will happen if you hold an object in front of the light coming out of the torch. Would you continue to see the spot of light on the screen? Note your prediction in Table 11.1.

Table 11.1: Light through different materials

Material	Transparent / Translucent / Opaque	Light will pass fully / partially / not at all
Material	Transparent / Translucent / Opaque	My prediction	My observation
Cardboard
Paper
Glass
Tracing paper
Thick cloth
…
…

Answer

The prediction should follow from the kind of material:

Glass or clear plastic — yes, the spot of light will still be seen, almost as bright as before.
Tracing paper or thin cloth — the spot will still be there but dim and blurred.
Cardboard, thick cloth or a steel plate — no, the spot will disappear and a dark patch (a shadow) will take its place.

Tip: A prediction is not a guess made after the event. Write it in the table before you put the object in the beam — that is what makes the next step a real test.

Q3.

Was your observation the same as your prediction? What conclusions could you draw?

Answer

For most objects the observation matches the prediction. A surprise or two is normal — thin paper often lets more light through than expected, and a coloured transparent sheet lets light through but changes its colour.

The conclusions are:

Transparent materials → light passes almost completely
Translucent materials → light passes partially
Opaque materials → light does not pass at all

Why it happens: In a transparent material the light finds a clear straight way through. In a translucent material the light is scattered again and again inside, so only a part of it comes out and it comes out spread in all directions — which is why the patch looks dim and blurred. In an opaque material the light is completely absorbed or reflected at the surface, so none of it gets through.

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