The frequency of waves emitted from a radar is 750 MHz. The frequency of reflected wave from the aeroplane as observed at the radar station is increased by 2.5 KHz. What is the speed of aeroplane

Options

A. `4 Kms^(-1)`
B. `2 Kms^(-1)`
C. `1 Kms^(-1)`
D. `0.5 Kms^(-1)`

Answer

D

Explanation

`(Deltan)/(n) = (2v_(s))/(v)`
`(2.5 xx 10^(3))/(750 xx 10^(6)) = (2 xx v_(s))/(3 xx 10^(8))`
`(2.5 xx 10^(3))/(7.5 xx 10^(8)) = (2v_(s))/(3 xx 10^(8))`
`2v_(s) = 10^(3)`
`v_(s) = (1)/(2) xx 10^(3) = 0.5 km//s`