In How to know, about science and technology series we will provide you information about science and technology, We are in making part of series and every part will contain 8-10 scientific questions and answer !
HOW DOES COLOUR TELEVISION WORK?
If you look closely at a colour A television picture, you will see that it is made up of tiny red, green and blue dots or stripes. These three colour mix together when you look at the screen from a distance to give a full-colour picture.
A colour camera produces three vision signals corresponding to the red, green and blue light in the scene. A colour set receives these three signals and sends them to three electron guns, Three electron beams seen the screen, one for each colour.
HOW VIDEO DOES A RECORDER WORK?
You can record a television programme A on a video cassette using a video recorder. The video cassette contains tape like a tape cassette.
It records the electric signal coming from the television aerial It records vision or video signals as magnetic patterns in a track along the tape.
In fact, the tape does not move quickly, instead, the head does. There are two heads mounted in a rotating drum, around which the tape moves. The heads spin rapidly as the drum passes along the tape, recording the vision signal in a series of diagonal tracks across the tape.
WHAT IS A VIDEO DISC?
A video disc is like a gramophone A record except that it has pictures recorded on it as well as sound. To see the film on the disc.
you play it on a video disc player connected to a television set. You cannot make your own video recordings on a video disc player. You can only play what is recorded on the disc.
There are several different video disc systems, One has a spiral groove in the record and a pickup with a stylus that rests in the groove. The picture signal is recorded as a sequence of electric charges that is detected by an electrode in the stylus.
HOW DOES AN AQUALUNG WORK?
An aqualung is used by a diver to swim freely underwater. The diver carries a cylinder of compressed air on his or her back. Air from the cylinder goes to a mouth-piece. This allow the diver to breathe air in from the cylinder.
For the diver to be able to breathe easily, the pressure of the air must be equal to the pressure of the water around the diver. A flexible diaphragm moves in and out to regulate the air pressure as the diver breathes.
HOW DOES A PARACHUTE WORK?
When a parachute opens, it billows A out above the parachutist, The large canopy of the parachute pulls against the air and slows the fall, The parachutist can pull on lines attached to the canopy to try and land in a particular place.
The parachute is packed carefully with a pilot chute that pulls out the main canopy The canopy may have gaps that allow the air through in a controlled flow. The air resistance of the canopy cancels out the weight of the parachutist.
HOW DO MAGNETS WORK?
Inside a magnet are lots of very tiny magnets. These are not separate objects, but very small parts of the magnet that each act like a tiny magnet, In a magnet, these tiny magnetic parts line up in rows.
The magnetic parts are called domains. An unmagnetized material contains domains, but their magnetism points in different directions, so that the magnetism of each domain is cancelled out by other domains, so the material has no overall magnetism.
HOW DOES ELECTRICITY FLOW ALONG A WIRE?
When electricity flows in a wire, tiny particles called electrons move through the wire. Each electron has a very small electric charge. As the electrons arrive, they produce electricity. To make a bulb in a room light up, about two million million million electrons flow every second.
The electrons come from a source of electricity like batteries or the generators. Each electron has a negative electric charge. The electrons leave the negative terminal and flow through the wire to the positive terminal to complete an electric circuit.
HOW DOES A CAR BATTERY WORKY?
A car battery does not run out of A electricity, since it can be recharged, The battery contains plates bathed in acid. The acid changes the material in the plates and makes them produce electricity. Feeding electricity back into the battery changes the plates back to the first material.
The plates of a car battery are arranged in pairs. One plate in each pair is made of spongy lead and the other is lead oxide, The pairs are suspended in dilute sulphuric acid, Separator plates keep them apart, and dividers group the plates into cells within the battery.
HOW DOES AN ELECTRIC MOTOR WORK?
When you switch on an electric motor, it makes something rotate, This could be the wheels of a toy train, for example. The electric current makes a wire coil inside the motor become magnetic. A magnet then makes the coil turn, and this powers a shaft.
The electric current flows from a battery through a coil suspended between the
poles of a magnet. The coil produces a magnetic field whose poles move towards the poles of the magnet. As a result, the coil rotates.
HOW DOES A TRANS-FORMER WORK?
A transformer changes the voltage A of an electric current. Inside the transformer, the current enters a coil and the coil produces a magnetic field. The field makes another current flow in another coil in the transformer.
A transformer increases or decreases the voltage of an alternating current. This kind of current reverses its direction of flow many times a second.
Transformers are used to produce electricity at very high voltage for long distance transmission. This voltage is then lowered in more transformers before reaching homes.
HOW DOES AN ELECTROMAGNET WORK?
An electromagnet is a kind of magnet A worked by electricity. Its magnetism can be switched on and off. It contains a coil of wire wound around an iron bar. When an electric current flows through the coil, the bar becomes strongly magnetic.
The iron core inside the coil of an electromagnet produces a much stronger magnetic field than the coil alone. This is because the coil magnetizes the iron the instant that the current is switched on. However, the iron core does not keep this magnetism when the electromagnet is switched off. It is demagnetized immediately.
Also Read –
- Science And Technology Question & Answer – Part 1
- Science And Technology Question & Answer – Part 2
- Science And Technology Question & Answer – Part 3
- Science And Technology Question & Answer – Part 4
- Science And Technology Question & Answer – Part 5
- Science And Technology Question & Answer – Part 6
- Science And Technology Question & Answer – Part 7
- Science And Technology Question & Answer – Part 9
- Science And Technology Question & Answer – Part 10
- Science And Technology Question & Answer – Part 11
- Science And Technology Question & Answer – Part 12