Sir, 1)Microwaves are directed normally at a plane metallic reflector. A detector moving along the normal to the reflector travels 15 cm from the first to the 11th successive of minimum intensity. What is the frequency of the microwave?(velocity of microwaves = 3 x 10^8 m/sec) I solved it in the following way: The incident and the reflected microwaves superimpose to produce standing waves. The distance between the first and the 11th minimum is given that it is 15 cm. Therefore, 0.15 = 10 x (lambda/2) Lambda = 0.03 meters Frequency = (3 x 10^8)/ 0.03 = 10^10 Hz Is it right? 2)Two waves of same frequency travel in opposite directions in a medium with amplitudes 3 units and 2 units respectively. What is the ratio of the amplitudes at an antinode and a node in the stationary wave? I think it is infinity because at the antinode it has maximum amplitude and at the node it is zero. Is it right?