Final answer:
The observed wavelength of a spectral line can be used to determine the speed and direction of motion of a star using the Doppler effect equation. However, without the unshifted wavelength, we cannot calculate the velocity.
Step-by-step explanation:
The observed wavelength of a spectral line can be used to determine the speed and direction of motion of a star using the Doppler effect equation. The equation is given by:
v = c * (△λ / λ)
Where:
- v is the velocity of the star
- c is the speed of light (approximately 3.0 x 10^8 m/s)
- △λ is the difference in wavelength between the observed wavelength and the unshifted wavelength (in meters)
- λ is the unshifted wavelength (in meters)
In this case, the observed wavelength is 475nm. To calculate the velocity, we need the unshifted wavelength. Since it is not provided, we cannot determine the speed and direction of motion of the star.