Chapter 5, Problem 1QP

To determine

The change that happens on the Earth when the Sun instaneously stopped giving off light.

Answer to Problem 1QP

Option (b) is the correct answer.

Explanation of Solution

The time taken by sunlight to reach the Earth is,

    $t=\frac{\text{distance between Earth and Sun}}{\text{velocity}}$

The distance between the earth and the Sun is $1.5\times {10}^{11}\text{m}$. And the speed of light is $3\times {10}^8\text{m}/\text{s}$.

Then the time taken is,

    $\begin{array}{c}t=\frac{1.5\times {10}^{11}\text{m}}{3\times {10}^8\text{m}/\text{s}}\\ =500\text{s}\times \frac{1\text{min}}{60\text{s}}\\ =8.3\text{min}\end{array}$

Conclusion:

Since the time taken is $8.3\text{min}$ option (b) is the correct answer.

Since the time taken for the sunlight to reach the Earth is $8\text{min}$ option (a) is incorrect.

Since the time taken for the sunlight to reach the Earth is $8\text{min}$ option (c) is incorrect.

Since the time taken for the sunlight to reach the Earth is $8\text{min}$ option (d) is incorrect.