Question

Light travels with a speed of $3\times {10}^8{ms}^{-1}$. The distance travelled by light in $1$ femto second is:

• A. $0.03mm$
• B. $0.003mm$
• C. $3mm$
• D. $0.0003mm$

Answer 1

The correct option is D $0.0003mm$

1 femto second = ${10}^{-15}$ second

thus light travel in 1 femto second $={10}^{-15}\times 3\times {10}^8=3\times {10}^{-7}m=0.0003mm$