Answer key

Prepared by: learnloophq@gmail.com

Last edited 26 days ago by Learn LoopHQ.

Chapter: 06. Light

⁠

I. Multiple Choice Questions

c. A lit candle

b. Rectilinear propagation of light

b. Real and inverted

c. Opaque

a. Between the Sun and the Moon

II. Fill in the Blanks

energy

rectilinear propagation of light

opaque

umbra

new moon

III. True/False Questions

T (True)

F (False)

IV. Short Answer Questions

Luminous objects are those that produce or emit light of their own, such as the Sun or a lit bulb.

A clear glass window does not cast a shadow because it is a transparent object, allowing light to pass through completely without obstruction.

Magnification in a pinhole camera refers to the ratio of the size of the image formed to the actual size of the object.

The two main types of natural shadows or eclipses are solar eclipse and lunar eclipse.

Shadows appear shortest at noon because the Sun is directly overhead at its highest point, causing the light rays to fall almost vertically, resulting in a very small projected shadow.

V. Diagram-Based Questions

Question 1:

This setup is designed to illustrate the property of rectilinear propagation of light.

No, the person will not be able to see the candle flame clearly. This is because light travels in straight lines, and the bent tube obstructs the straight path of light from the candle flame to the observer’s eye, preventing the light from reaching it.

Question 2:

The two distinct regions of the shadow are the umbra (the central, darker part) and the penumbra (the lighter, outer part).

An extended light source creates both umbra and penumbra regions. The umbra is the area that receives no light at all from the entire source, while the penumbra is the area that receives some light from parts of the extended source, resulting in partial darkness.

VI. Long Answer Questions

A simple pinhole camera consists of a hollow rectangular box. A very small hole (pinhole) is made on the center of one face, and the inside of the box is blackened to prevent unwanted light reflections. The opposite face is covered with a translucent screen, like tracing paper. When an object is placed in front of the pinhole, light rays from each point of the object travel in straight lines through the tiny pinhole. These rays cross at the pinhole, causing an inverted (upside down) and real image of the object to be formed on the screen.

A total solar eclipse occurs when the Moon comes directly between the Sun and the Earth, blocking all sunlight and casting its umbra (darkest shadow) on a small region of the Earth, making the Sun completely invisible there. A total lunar eclipse occurs when the Earth comes directly between the Sun and the Moon, casting its umbra onto the Moon. In this case, the Earth’s shadow completely covers the Moon, making it invisible or appearing as a dull red disc from Earth.

VII. Identifying and Differentiate Concepts

Wood: Opaque

Clear Glass: Transparent

Butter Paper: Translucent

Steel Spoon: Opaque

Frosted Glass: Translucent

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