Question

Why does a matchstick catch fire when rubbed on the rough surface of the

box?


2. Why does not a screwdriver used by electricians have metal handle?


3. Explain why we are not able to hear the explosions taking place in the sun?


4. What would happen if we increase the size of the hole of the pinhole

camera? ​

Answer 1

1. On rubbing the match stick in the rough surface, the friction converts this work into heat. The heat raises the temperature of the chemical present on the match stick head to its ignition temperature. Due to this the chemical substance catches fire and the match stick starts burning.
2. The screwdriver use by the electrician have a plastic or a wooden handle because the front portion of screwdriver is made up of iron which is a good conductor of heat and electricity,so to prevent electric shock the handles are made of non metals such wood and plastic as they are insulator.
3. Sound needs a material medium for its propagation from one place to another place. In other words sound cannot travel through vacuum. Since there is a region between the planets and the earth, where there is a vacuum, so the sound of explosions taking place on other planets cannot pass through this vacuum.
4. If the size of the hole in a pinhole camera is as big as the size of a green gram then the sharpness in the image decreases. The image becomes thick and the image is blur. If the size of the hole of a pinhole camera increases then more light enters and disturbs the formation of the image.