Question

Light travels 1 foot in approximately how much time?

• A. 1 second
• B. 1 hour
• C. 1 nano-second
• D. 1 minute

Answer 1

The correct option is C 1 nano-second

$\text{Speed}=\frac{\text{Distance}}{\text{Time}}$

For light, speed is: $v=3\times {10}^{8}m{s}^{-1}$

$1\text{foot}=0.3048m$

Time taken by light to cover 1 foot:
$t=\frac{0.3048}{3\times {10}^8}s$
$t\approx {10}^{-9}s$
$t\approx 1ns$