Electromagnetic Waves Physics Example 2

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Example 2

medium
How long does it take light from the Sun to reach Earth? The Sun-Earth distance is 1.5×1011 m1.5 \times 10^{11} \text{ m} and c=3×108 m/sc = 3 \times 10^8 \text{ m/s}.

Solution

  1. 1
    Use t=dct = \frac{d}{c}.
  2. 2
    t=1.5×10113×108=500 st = \frac{1.5 \times 10^{11}}{3 \times 10^8} = 500 \text{ s}
  3. 3
    500 s=8 min 20 s500 \text{ s} = 8 \text{ min } 20 \text{ s}

Answer

t=500 s≈8.3 minutest = 500 \text{ s} \approx 8.3 \text{ minutes}
Despite traveling at the fastest speed possible, light takes over eight minutes to reach us from the Sun. When we look at the Sun, we see it as it was 8.38.3 minutes ago.

About Electromagnetic Waves

Transverse waves consisting of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of propagation.

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