Hello, Science enthusiasts, today I am going to explain you about the fact which we see in our daily life. We go to schools and colleges. We see blackboard there. When our teachers explain us something by writing on them with a chalk we may here some sounds emitted. Many of you hear this sound. Now I will explain to you why this happens. Please subscribe to our Email and Push Notifications service to get such interesting stuff to your inbox and mobile.
Our teachers use to teach lessons with the help of the blackboard. The classroom is incomplete with a teacher and board of course students. We can write on the blackboard with the help of chalk piece. This is made up of “Calcium Carbonate”.
For the first time “James Pillans” invented the blackboard in 1800’s. He worked as Headmaster for a school in Edinburgh, Scotland. The term blackboard represents their a wooden board which is in black color. Nowadays there are many colors in the boards as green, white. We use the chalk to write on green color board as similar on the blackboard.
The another color in board i.e.., is white. We use the marker to write on that board. Daily the teachers use the blackboard. While they writing on the board with chalk piece we may hear some sound which frequency is high in the audible range. Those sounds are not comfortable to hear. As we discussed past the sound which is not comfortable to hear is called as ‘Noise‘. I am here to make you understand actual why those sounds are emitted.
How the science involved in emitting sound when we write on the blackboard:
While the teacher writing on the blackboard the friction come into existence between the chalk piece and board. Due to this friction acting on chalk it will stop for part of second. Then the force acts on the chalk piece because of the writer. Due to this force, it overcomes the friction force and moves on. At this time the chalk piece will tend to the vibrations. Due to these vibrations, some sound waves are emitted into the air.
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These emitted sound waves frequency is between the audible ranges. It means its frequency is between 20 Hz to 20 KHz. Thus we can hear some different type of sound when the teachers writing on the blackboard. By hearing those sounds we all will laugh for some time. We see these situations in our school life itself. Really those days was memorable to everyone.
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