Hertz,in his historical experiment ,produced stationary electromagnetic waves and measured the distance between two successivendoes.Explain,how this measurement enabled him to show that the electromgnetic waves travelled with the same speed as the speed of lght.

Draw a labelled diagram of Hertz's experiment set up to produce electromagnetic waves. Explain the generation of electromagnetic waves using this set up.

In each of the following problems, clearly state what the relevant and irrelevant factors are while going through Steps 1, 2 and 4 given in this chapter :- Suppose a car starts from a place A and travels at a speed of 40 km/h towards another place B. At the same instance, another car starts from B and travels towards A at a speed of 30 km/h. If the distance between A and B is 100 km, after how much time will the cars meet?

Two particles, each of mass mand speed v, travel in opposite directions along parallel lines separated by a distance d. Show that the vector angular momentum of the two particle system is the same whatever be the point about which the angular momentum is taken.

Earthquakes generate sound waves inside the earth. Unlike a gas, the earth can experience both transverse (S) and longitudinal (P) sound waves. Typically the speed of S wave is about 4.0 km s^-1 and that of P wave is 8.0 km s^-1 A seismograph records Pand Swavesfrom an earthquake. The first Pwave arrives 4 min before the first S wave. Assuming the waves travel in straight line, at what distance does the earthquake occur ?

A motor boat going upstream in a river travels the distance between two cities in six hours. The same distance is travelled downstream in a river in 5 hours. If the Year Timing (in seconds) 1972 51.08 49.28 48.88 48.83 48.65 48.83 48.25 49.11 49.41 1976 1980 1984 1988 1992 1996 2000 2004 speed of the river is 2 km/h. Find the speed of boat in still water.