Answer:
Step-by-step explanation:
The problem is based on the concept of Doppler's effect of em wave .
Expression for apparent frequency can be given as follows
n = N x (V - v ) / ( V + v )
n is apparent frequency , N is real frequency , V is velocity of light and v is velocity of cloud.
n = 6 x 10⁹ ( 3 x 10⁸ - 8.52 ) / ( 3 x 10⁸ + 8.52 )
= 6 x 10⁹ ( 3 x 10⁸ ) ( 3 x 10⁸ + 8.52 )⁻¹
= 6 x 10⁹ ( 3 x 10⁸ ) ( 3 x 10⁸)⁻¹ ( 1 + 8.52/3 x 10⁸ )⁻¹
= 6 x 10⁹ ( 1 - 8.52/3 x 10⁸ )
= 6 x 10⁹ - 6 x 10⁹x 8.52/ (3 x 10⁸ )
= 6 x 10⁹ 1 - 170 .
So change in frequency = 170 approx.