Electromagnetic induction was discovered by
- A.Hans Christian Oersted
- B.Michael Faraday
- C.Alessandro Volta
- D.James Watt
Correct answer
Explanation
The correct answer is B, Michael Faraday. In 1831 Faraday showed that when the magnetic flux linked with a closed coil changes, whether by moving a magnet, moving the coil or changing the current in a nearby coil, a current is induced in it. This discovery is the basis of the generator, the transformer and almost the whole of electrical power engineering.
Option A, Oersted, made the complementary discovery eleven years earlier, in 1820, when he found that a compass needle is deflected near a current-carrying wire, showing that a current produces a magnetic field. Option C, Volta, invented the voltaic pile, the first electric battery, and the volt is named after him. Option D, James Watt, was an engineer of the steam engine and gave his name to the unit of power, but he had nothing to do with induction. The pair worth fixing in memory is Oersted in 1820 and Faraday in 1831.
Read the full article: Electricity and Magnetism: Laws, Rules and PYQs
Practice Questions
View allIf the potential difference across the ends of a conductor is halved, what happens to the current flowing through it?
- A.It gets increased
- B.It gets doubled
- C.It gets decreased
- D.It gets halved
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By Ohm's law, at a constant temperature the current through a conductor is directly proportional to the potential difference across its ends, since the current equals the potential difference divided by the resistance.
Read the full explanation →What is the work done to move a unit charge from one point to another in an electric circuit carrying some current, between those two points?
- A.Pressure distance
- B.Potential difference
- C.Potential distance
- D.Pressure difference
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The potential difference between two points in a circuit is defined as the work done in moving a unit positive charge from one point to the other.
Read the full explanation →Which of the following is NOT based on the heating effect of current?
- A.Electric heater
- B.Electric bulb (with filament)
- C.Electric iron
- D.Microwave
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A microwave oven does not cook by passing a current through a resistance. It generates microwaves in a magnetron, and these waves make the water molecules in the food rotate rapidly, so the food heats from within by dielectric heating.
Read the full explanation →A 12 V battery is connected across an unknown resistor. If a current of 2 mA is flowing through the circuit, the value of the resistance is _________ .
- A.600 ohm
- B.6 ohm
- C.6000 ohm
- D.60 ohm
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By Ohm's law the resistance equals the potential difference divided by the current. Here the current must first be converted into the base unit: two milliampere is 0.002 ampere.
Read the full explanation →Thin wires of which of the following metal is used for making the filament of electric bulbs?
- A.Tungsten
- B.Silver
- C.Nichrome
- D.Copper
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Tungsten has the highest melting point of all metals, well above three thousand degrees Celsius, so a thin tungsten wire can be heated until it glows white without melting.
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