Question

A student wants to find if a star if moving away from the earth or towards the earth. Which of the following principle he can use?

• A. Newton's law of universal gravitation
• B. Red shift of light from other galaxies
• C. The fact that every element of atomic number greater than 83 is radioactive
• D. The zeroth law of thermodynamics
• E. Mass-energy equivalence

Answer 1

The correct option is B Red shift of light from other galaxies

Red shift happens when light from an object increases in wavelength. It occurs whenever a light source moves away from an observer.

Blue shift happens when light from an object decreases in wavelength. It occurs whenever a light source moves toward an observer.