Waste less time on Facebook — follow Brilliant.

Physics fact for those who take photos of themselves in front of a mirror

Does your bathroom mirror show you older or younger than you actually are ? Compute an order of magnitude estimate for the age difference

The image formed of an object placed in front of a flat mirror is as far behind the mirror as the object is in front of it. A flat mirror produces an image that has an apparent front-back reversal

The image of the bathroom mirror shows you younger than you actually are

Let the distance between the observer and the mirror be 15 cm

s=15 cm = 0.15 m

the reflected image seen by the person is from the light that traveled from the person to the mirror and back. The time interval is calculated using the following formula:

t= (2s)/(c)

c= speed of light = 3.00 * 10^8

the reflected light gives the image of what the person had been earlier

t= (2 * 0.15)/(3.00 * 10^8) = 10^-9 seconds

Therefore, the person appeared as 10^-9 seconds younger than he actually is

Note by Jaber Al-arbash
3 years ago

No vote yet
1 vote


Sort by:

Top Newest

wow..never thought of that thing

Kelvin Gonzales - 2 years, 12 months ago

Log in to reply

Wow! Never thought that...amazing

Krishna Sharma - 3 years ago

Log in to reply


Problem Loading...

Note Loading...

Set Loading...