Question

1. If a CRT is designed so that the spot traverse the indicator face in 900µsec, what range could be indicated by a spot deflection half-way across the indicator?

2. Increasing the transmit power of a radar by a factor of 5 will increase the maximum range by what percent?

3. An observer at rest near the source of the sound of frequency 684Hz. Another source of sound 676Hz is moving toward the observer at 2m/s. If the speed of the sound waves in air is 340m/s, what is the beat frequency heard by the observer?

4. An ambulance moves at 72KPH while sounding a siren with a frequency of 1500Hz. Motorcyclists move at speed of 20m/s in opposite directions with ambulance. If the speed of sound in air is 340m/s, what is the ratio of frequencies heard by motorcyclists when approaching and away from the ambulance?

5. A fire truck emits an 880Hz siren. As the truck approaches an observer on the sidewalk, he perceives the pitch to be 950Hz. What pitch does he hear after the truck passes and moving away? Assume the truck’s velocity remains constant and the velocity of sound in air is 340m/s.

6. Two cars approach each other at 50m/s when one car starts to beep its horn at a frequency of 475Hz. What is the wavelength of the horn as heard by the other driver? Assume the speed of sound in air to be 343m/s.

Answer 1

Ans of question 5 is 820 Hz.