A radio wave leaves a station's antenna, and a gamma ray leaves a distant star. Both cross empty space. Tove wonders which one crosses it faster.
Neither wins. This lesson names the one speed every electromagnetic wave shares.
Through a vacuum, every electromagnetic wave travels at the same speed.
The radio wave and the gamma ray cross empty space at exactly the same speed.
That speed is 3.00 × 10⁸ m/s.
A greater frequency does not raise it, and a longer wavelength does not lower it: in a vacuum, the speed is the same for every electromagnetic wave.
Its symbol is c, so c stands for 3.00 × 10⁸ m/s.
The name says light, but c belongs to the whole family: radio waves, visible light, and gamma rays all cross a vacuum at c.
Inside a material, light travels a little slower; c is the speed through a vacuum.
A gamma ray and a flash of visible light cross the same stretch of vacuum. Compare their speeds.
Both are electromagnetic waves.
Every electromagnetic wave crosses a vacuum at the speed of light, 3.00 × 10⁸ m/s.
Their speeds are equal: both travel at 3.00 × 10⁸ m/s.
Microwaves from a satellite and ultraviolet light from the Sun both cross empty space. Tove expects the ultraviolet, with its greater frequency, to be faster. What are the actual speeds?
Frequency does not change the vacuum speed.
Every electromagnetic wave crosses a vacuum at the speed of light.
Both travel at 3.00 × 10⁸ m/s: the ultraviolet is not faster.
Rurik says: 'In a vacuum, every electromagnetic wave travels at the same speed.' Is Rurik correct?
What is the speed of light in a vacuum?
Selby says: 'An electromagnetic wave with a greater frequency crosses a vacuum faster than one with a lower frequency.' Is Selby correct?
Infrared light and X-rays both cross a stretch of vacuum. Which statement about their speeds is true?
Which statement about the symbol c is correct?
A spacecraft near Saturn sends a radio signal and a flash of visible light toward Earth at the same moment. Which statement about their arrival is true?