11. reflecting telescopes are popular because they're than a refracting telescope. a. smaller b. more durable c. more powerful d. easier to build student cincorrect reference: section 5.3 20. in any one material, all electromagnetic waves have the same a. amplitude. b. wavelength. c. velocity. d. frequency. student dincorrect reference: section 5.4

sonar - device which is used to find the submit submarines, sankalp ship. sonar waves consists of a transmitter and detector which are installed in the observation centre on board of a ship. the ultrasonic waves are sent into the sea at high frequency about 1000 khz in all direction.

the moon affects the earth gravitation ally, causing certain motions of that body and also producing tides in its ocean and atmosphere. the tidal wave in our atmosphere is, however, far too minute to be an effective cause in any known meteorological phenomenon.

explanation: