SECTION I
A. Choose the correct option
- Natural sources of light include
(a)Sun (b) Stars (c) Fires (d) All of these.
Answer. (d) All of these
- Which of the following does not allow light to pass through them?
(a) Book (b) Mirror (c) Computer (d) All of these
Answer. (d) All of these
- Which of the following is transparent?
(a)Glass (b) Bed (c) Copy (d) None of these.
Answer. (a)Glass
- Light travels in a
(a)Zigzag path (b) Straight line (c) Circular path (d) Curved line.
Answer. (b) Straight line
- The color of the shadows is
(a)Red (b) orange (c) black (d) white.
Answer. (c) Black
B. Match the following
- Source of the light → 4. Candle
- Translucent → 5. Tracing paper
- Clean water → 1. Transparent
- Dark patch → 2. Shadow
- Orbit → 3. Fixed path of the earth around the sun
C. Short Answer Questions
1. Define the source of light. Name its two types with examples.
Answer. A source of light is an object that emits its own light. There are two types:
- Natural sources: Sun, stars
- Artificial sources: Bulbs, candles
2. Write an important property of light.
Answer. Light travels in a straight line. This property is called the rectilinear propagation of light and is the reason shadows form when an object blocks light.
3. Why can we see through a glass, but not through a bat?
Answer. Glass is transparent and allows light to pass through completely, making objects visible. A bat is opaque and blocks light entirely, preventing visibility.
4. Define shadow. What are the conditions required for the formation of a shadow?
A shadow is a dark area formed when an opaque object blocks the path of light. The conditions for shadow formation are:
- A source of light
- An opaque object
- A surface for the shadow to fall on
5. Name the two types of movement of Earth.
The two types of Earth’s movement are:
- Rotation: Spinning on its axis, causing day and night
- Revolution: Orbiting around the Sun, causing seasons
D. Long Answer Questions
1. Define transparent, translucent, and opaque objects.
- Transparent objects: Allow light to pass through completely, e.g., glass, clear water.
- Translucent objects: Allow partial light to pass through, e.g., frosted glass, tracing paper.
- Opaque objects: Do not allow light to pass through, e.g., wood, metal.
2. Discuss the formation of shadows at different times of the day.
Shadows form when light is blocked by an opaque object. The position and length of shadows change throughout the day due to the Sun’s position in the sky:
- Morning and evening: Shadows are long because the Sun is low.
- Noon: Shadows are short because the Sun is overhead.
3. How is day and night caused? Explain with the help of a diagram.
Day and night are caused by Earth’s rotation on its axis. As Earth rotates, the part facing the Sun experiences day, while the part away from the Sun experiences night. The rotation takes 24 hours to complete one full turn.
4. Define solar eclipse. How is it formed?
A solar eclipse occurs when the Moon comes between the Sun and Earth, blocking sunlight partially or completely. It happens during the new moon in this condition the Sun, Moon, and Earth comes in a straight line.