Science Focus - the home of BBC Science Focus Magazine
Does a USB drive get heavier as you store more files on it? © Getty Images

Does a USB drive get heavier as you store more files on it?

Subscribe to BBC Science Focus Magazine and get 6 issues for just £9.99

Paradoxically, the more you save on a flash drive, the lighter it gets.

Asked by: Ben Chelski, Colchester

Advertisement

Believe it or not, they get lighter. USB drives use Flash memory, which means the the ones and zeros of your data are stored on transistors.

When you save data, a binary zero is set by charging the float gate of the transistor, and a binary one is set by removing the charge.

To charge it, we add electrons, and the mass of each electron is 0.00000000000000000000000000091 grams.

This means that an empty USB drive (which mostly holds zeros) weighs more than a full USB drive (which has ones and zeros). Add data, reduce the weight.

However, you would need to weigh more USB drives than exist on the planet together at once before the difference in weight became easily measurable.

Read more:

Advertisement

Authors

Dr Peter Bentley is a computer scientist and author who is based at University College London. He is the author of books including 10 Short Lessons in Artificial Intelligence and Robotics and Digital Biology: How nature is transforming our technology and our lives.

Advertisement
Advertisement
Advertisement

Sponsored content