A tsunami is very large sea wave that is generated by a disturbance along the ocean floor. This disturbance can be an earthquake, a landslide, or a volcanic eruption. A tsunami is undetectable far out in the ocean, but once it reaches shallow water, this fast-traveling wave grows very large.

Tsunamis occur when a major fault under the ocean floor suddenly slips. The displace rock pushes water above it like a giant paddle, producing powerful water waves at the ocean surface. The ocean waves spread out from the vicinity of the earthquake source and move across the ocean until they reach the coastline, where their height increases as they reach the continental shelf, the part of the Earth’s crust that slopes, or rises, from the ocean floor up to the land.

Tsunamis wash ashore with often disastrous effects such as severe flooding, loss of live due to drowning, and damage to property.

Sound Recording and Reproduction


Sound recording and reproduction are two separate processes used to record, store, and play back sounds. Sound recordings use microphones to pick up sound waves in the air. The pressure changes associated with the waves are converted into electrical signals, which can be coded and stored for future access. Sound reproduction, or playback, uses additional devices to retrieve the stored information and convert it back into electrical signals. The signals are then sent to a loudspeaker, which converts them back into sound.

To record sound, a microphone changes the acoustic energy of sound waves in the air into electrical signals. Inside a microphone is thin, flat, metallic surface, called a diaphragm that is suspended in a magnetic field. When a sound wave reaches the microphone, the air pressure changes around the diaphragm causing the diaphragm to move. This movement within a magnetic field creates an electrical signal. The signal is then transferred to a storage medium, such as a cassette tape, compact disc (CD), or phonograph record.

To reproduce sound, a playing device-such as a CD player, cassette deck, or phonograph accesses the stored data. The playing device reads the data and converts the information back into electric energy. The electrical signal is sent to a loudspeaker, which has a diaphragm housed in a magnetic field in much the same way as a microphone’s diaphragm is housed. The electrical signal creates a disturbance in the magnetic field. These resultant variations in the magnetic field cause the diaphragm to move. As the diaphragm moves, it pushes out and pulls in, creating changes in air pressure to recreate the sound that was originally recorded.

Sound recordings and reproduction form the foundation of many industries, including entertainment, communications, and multimedia businesses. Recording and reproduction of sound allow people to play their favourite music, whether it was recorded yesterday or many years ago. Radio networks rely on sound recording and reproduction for storing news and other types of programming. Television and motion pictures combine images with music, speech, and sound effects to provide the viewer with an enriched experience. Computer programs, multimedia software, and video games also use sound to make programs more engaging.

Making Paper from Woodchips

Do you have any paper in your bag? It may seem like a silly question but do you know how to make paper? What is paper made of? Right! And how is about ‘wood chipping’? Have you ever heard about it? Well, wood chipping is a process used to obtain pulp and paper products from forest trees.

First of all, the tops and branches of the trees are cut out and then the logs are taken to the mill. At the mill the bark of the logs is removed and the logs are taken to a chipper which cuts them into small pieces called woodchips. The woodchips are then screened to remove dirt and other impurities. Hmm … at this stage they are either exported in this form or changed into the pulp by chemicals and heat. Oh, I almost forgot, the pulp is then bleached and the water content is removed. Finally, the pulp is rolled out to make paper.

Considering the complexity of making paper, let’s appreciate any paper on our hands. Use it more effectively. Thank you for listening. Bye.