12. Light and sound

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12. Light and sound


Fill in the blanks. 
1. Objects which cannot give out their own light are called Non - luminous. 
2.Trandparent  object allow light to pass through them completely. 
3. Reflection is bouncing back of light from a smooth shiny surface. 

Write true or false. 
1. Sound does not require any medium to travel. (F) 
2.The sound of loudspeaker is an unpleasant sound. (T) 
3.sound travels through air in the form of particles. (F) 

Let us practise
1. Fill in the blanks. 
a. Noise is produced by irregular  sound waves. 
b. Sun is the main source of heat and light on earth. 
c. When light hits a surface and cannot pass through it, the surface is called opaque. 
d. Sound is produced due to vibration of objects. 

2. Write 'T' for true and 'F' for false. 
a. Honking car is an example of a pleasant sound.(F) 
b. Light cannot bend around the cornera. (T) 
c. Water is a translucent material. (F) 
d. Moon is a luminous object. (F) 

3.Match the following. 
Hear are the answers 
a. Luminous = lamp
b. Opaque = Aluminum foil
c. Translucent = sunglasses
d. Sound = vibration

Q4. Read the following two statements and choose the correct option. 
Statement 1. Candle is a luminous object. 
Statement 2. Luminous object give out light on their own. 
Ans. a. Both statements 1 and 2 are correct. 

Q5. Short answer type questions
Ans. Sound help us to communicate our thoughts. 

Ans. Light enable us to see objects around us. 

Ans. Sound travels through air in the form of waves. 

Ans. There are different types of sounds. Pleasant, unpleasant, soft and loud. 

Q6. Long answer type questions
Ans. Objects can be classified into two main categories based on their ability to emit light:

Luminous Objects
These objects emit their own light. Examples:
- Sun
- Stars
- Bulb
- Firefly

Non-Luminous Objects
These objects reflect light from other sources. Examples:
- Moon
- Planets
- Trees
- Books

Ans. Light always travels in a straight line. It is unable to bend around corners. You have probably noticed that light streams from clouds or trees travel in a straight line. 
Light travels in a straight line, shown by experiments like pinhole camera, torch and cardboard, and laser beam, where light passes through aligned holes or objects, demonstrating its linear path.

Ans. 
Opaque objects- when light hits a surface and cannot pass through it, the object is called opaque Example of opaque object include, table, book, aluminum, foil and ect. 

Translucent objects- The obo which allow light to pass through them partially are called translucent. Example of translucent object include tissue paper etc. 

Transparent objects- The objects which let the light pass through them completely are called transparent. Example of transparent objects include clear glass, water, plastic, trany bag etc. 









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