We use electromagnetic induction in many ways in our daily lives, in most cases without realizing it. One recent invention is a flashlight that works without a battery. Further, in air travel safety, electromagnetic induction is used to prevent dangerous metallic objects (such as knives and guns) from being carried on the planes.
(i) When was electromagnetic induction discovered? To which human quality do you attribute this discovery? Visualize the scenario prior to this discovery.
(ii) How does a batteryless flashlight work?
(iii) How are passengers screened at the airport?

Explanation

(i) Electromagnetic induction was discovered by Michael Faraday on 17th Oct, 1831 (just 186 years ago). Perseverance as Faraday had to struggle for six years to be successful in his endevour. There was no electricity (from generators) before that time. Life today is totally dependent on electricity, the eight wonder of modern civilized world. Look at the effects on our lives of a power failure lasting only a few hours and think of all the devices based on it: lights, radio, television, motors to drive the wheels of industry-the list is unending.
(ii) As the flashlight is shaken, its internal permanent magnet passes through a coil, inducing a current. This current alternates in direction and thus needs to be turned into dc before it can charge a capacitor. Once the capacitor is fully charged, it can be used to create a current through a light-emitting diode (LED), which in turn gives off light, typically for several minutes.
(iii) As a passenger walks through the arch of the airport metal detector, he is subjected to a series of magnetic field pulses. If he has a metal object on his person, the currents induced in the object create their own magnetic field "echo" that, when detected, gives the safety inspectors reason to check the passenger more thoroughly.