{{Short description|Change in a moving object's trajectory due to a collision or force field}} {{refimprove|date=November 2025}} {{Use dmy dates|date=January 2025}} thumb|upright=1.35|An object hitting a surface is an example of deflection.
'''Deflection''' is a change in a moving object's velocity, hence its trajectory, as a consequence of contact (collision) with a surface or the influence of a non-contact force field.<ref name=EduTinker>{{cite web|url=https://edutinker.com/glossary/deflection/|website=EduTinker|title=Deflection|date=October 31, 2023|access-date=November 7, 2025}}</ref> Examples of the former include a ball bouncing off the ground or a bat;<ref>{{cite book|url=https://books.google.com/books?id=K218AgAAQBAJ&pg=PA243&dq=%22Deflection%22+baseball+-wikipedia&hl=en&newbks=1&newbks_redir=0&source=gb|pages=243-247|title=Projectile Dynamics in Sport: Principles and Applications|first=Colin|last=White |year=2010|isbn=9781134027620|publisher=Taylor & Francis|access-date=November 7, 2025}}</ref> examples of the latter include a beam of electrons used to produce a picture,<ref name=EduTinker /> quantum deflection,<ref>{{cite journal |url=https://physics.aps.org/articles/v16/s114|title=Quantum Deflection Unraveled|date=August 8, 2023|journal=Physics|volume=16|page=s114|first=Ryan |last=Wilkinson|access-date=November 7, 2025}}</ref> or the relativistic bending of light due to gravity.<ref>{{cite web|url=https://physics.stackexchange.com/questions/768088/newtonian-light-deflection|website=Physics Stack Exchange |title=Newtonian light deflection|access-date=November 7, 2025}}</ref>
==Deflective efficiency== {{see also|shock (mechanics)|perfect mirror|absorption (electromagnetic radiation)}} An object's '''deflective efficiency''' can never equal or surpass 100%, for example: *a mirror will never reflect exactly the same amount of light cast upon it, though it may concentrate the light which is reflected into a narrower beam. *on hitting the ground, a ball previously in free-fall (meaning no force other than gravity acted upon it) will never bounce back up to the place where it first started to descend.
This transfer of some energy into heat or other radiation is a consequence of the theory of thermodynamics, where, for every such interaction, some energy must be converted into alternative forms of energy or is absorbed by the deformation of the objects involved in the collision.
== See also == * Electrostatic deflection * Coriolis effect * Deflection yoke * Impulse * Reflection
==References== {{reflist}}
==External links==
Category:Scattering Category:Collision
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