Exam-style question
Try this first
Which statement best describes the speed of light in vacuum according to special relativity?.
- A.It varies with the motion of the source.
- B.It is constant in all inertial frames.
- C.It depends on the observer's velocity.
- D.It is zero in a vacuum.
Model answer
What a good answer should say
- It is constant in all inertial frames.
Explanation
Why this works
Formula/rule: constancy of the speed of light in vacuum. Substitution: none.
Working: The second postulate of special relativity states that the speed of light in vacuum, c, is the same for all inertial observers, regardless of their relative motion. This means c ≈ 3.00 × 10^8 m/s in all inertial frames.
Answer: c is constant. Units/conclusion: c = 3.00 × 10^8 m/s, same in all inertial frames.
Common mistake
No common mistake is linked to this question yet.