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Why does an electric light bulb give off light?

A light bulb gives off light because an electric current is passed through its filament,a thread of tungsten metal thinner than a human hair, which then becomes white hot. Sir Joseph Swan (1828-1914) in the England and Thomas Alva Edison (1847-1931) in the United States constructed the first incandescent electric lamps in 1879. They succeed in preventing the rapid burning …

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Why does an automobile have a carburetor?

An automobile is driven by an internal combustion engine which will work properly only if the right amounts of petrol and air are mixed together. The carburetor is the part of the engine where the mixing takes place. The burning of fuel in the engine is a chemical reaction in which petrol combines with the oxygen of the air to …

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शुभ मुहूर्त

Shubh muhrat

एक समय की बात है – एक बहुत की भोला – भाला दम्पति था। पति – पत्नी, दोनों ही इतने ज्यादा भोले थे कि कई बार तो उनके निपट मूर्ख होने का भी संदेह होता था। एक रात में कुछ शोर सुनकर दोनों उठ बैठे। “मालूम होता है, घर में चोर घुस आए हैं,” आदमी फुसफुसाया। “क्यों भागवान, तुम्हे कुछ सुनाई …

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Why does alternating current repel while direct current attract objects?

A winding (conductor) carrying direct current (DC) produces a magnetic field akin to a permanent magnet. The current carried by this conductor is unidirectional and steady i.e. it does not change direction or vary in magnitude with respect to time. Hence, the effect is that of a permanent magnet which simply attracts objects near the coil. The case is different …

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Why does a magnet attract iron?

Magnets attract iron due to the influence of their magnetic field upon the iron. Before a piece of iron enters the magnetic field of a magnet, the polarization of the iron’s atoms is random. When exposed to the magnetic field, the atoms begin to align their electrons with the flow of the magnetic field, which makes the iron magnetized as …

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Why does a hair-cut not hurt?

All our senses are controlled by our nerves, which carry their messages to the brain. Therefore, any part of us that has nerves also has a sense of feeling. We might fall and cut ourselves, or have a tooth that aches. We are made well aware of pain because the damaged parts contain nerves. Our hair, however, does not contain …

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Why does a falling object have no weight?

Every body on this earth is attracted by the gravitational pull of the earth. A freely falling object has weight W=mg, where W-weight, m-mass of the object and g-acceleration produced due to the earth’s gravity. An object kept in a lift which falls freely, weighs zero on the weighing machine, but its actual weight is still mg. This happens because …

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