Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: Can you use light to attract or repel an item?

Learn more physics!

Most recent answer: 06/27/2019
Q:
Can you use light to attract or repel an item?
- CHRIS POLLAN (age 42)
Wills Point, texas, usa
A:

If you shine light directly on an object, it will only push not pull (except in very weird circumstances, in which the object's atoms have been prepared in special excited states).

However, if you pass a narrow beam of light just at the edge of a small object it will push or pulll the object sideways into or out of the beam, depending on the refractive index of the object.  This is the basis of optical tweezers.  The ability to manipulate individual molecules (or even parts of molecules) have made laser tweezers an important tool in biophysics.  The 2018 Nobel Prize in Physics was awarded to Arther Ashkin for the invention of optical tweezers.

jjt


(published on 06/27/2019)

Follow-up on this answer.