Exercise 15.4 Visualizing Solid Shapes NCERT Solutions Class 7

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Chapter 15 Ex.15.4 Question 1

A bulb is kept burning just right above the following solids. Name the shape of the shadows obtained in each case. Attempt to give a rough sketch of the shadow. (You may try to experiment first and then answer these questions).

Solution

Video Solution

What is known?

Some solids

What is unknown?

Shape of the shadow obtain in each case.

Reasoning:

A spherical object gives a circular shape shadow.

A cylindrical object gives a shadow of a line.

A cuboidal object gives a rectangular shape shadow.

Steps:

(i) A ball will give the shadow of a circle when tourch is above the ball.

(ii) A cylindrical pipe  will give the shadow of a line.

(iii) A book will give image of a rectangle.

Chapter 15 Ex.15.4 Question 2

Here are the shadows of some \(3-D\) objects, when seen under the lamp of an overhead projector. Identify the solid(s) that match each shadow. (There may be multiple answers for these!)

Solution

Video Solution

What is known?

Some shadow of solid shapes

What is unknown?

Solid shapes for each shadow

Reasoning:

A spherical object gives a circular shape shadow.

A cylindrical object gives a shadow of a line.

A cubical object gives a square shape shadow.

A cuboidal object gives a rectangular shape shadow.

A conical object gives a triangular shadow.

Steps:

Solids will be:

  (i) A ball or sphere will give shadow of a circle.

 (ii) A cube shape object like dice will give shadow of a square.

(iii) An ice- cream cone or a birthday cap will give the shadow of triangle.

(iv) A book or a cuboid shape object will give shadow of a rectangle.

Chapter 15 Ex.15.4 Question 3

Examine if the following are true statements:

(i) The cube can cast a shadow in the shape of a rectangle.

(ii) The cube can cast a shadow in the shape of a hexagon.

Solution

Video Solution

What is known?

Statements.

What is unknown?

Statement is true or not.

Reasoning:

A cubical object gives a square shape shadow when light is coming directly and it gives a rectangular shadow when light is coming diagonally.

Steps:

(i) The cube can cast a shadow in the shape of a rectangle is True because when the light is coming diagonally then it will cast shadow of rectangle.

(ii) The cube can cast a shadow in the shape of a hexagon is false as in either case cube will not cast shadow of hexagon as cube can cast shadow of square or rectangle and square and rectangle both have \(4\) sides but a hexagon has \(6\) sides.

  
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