I have always learned that if you accelerate an object with a force , the difference in kinetic energy of that object is equal to the work done by that force (if only 1 force occurs).
But I also learned that charges with an acceleration emit EM radiation.
Now I wonder how these 2 events go together, if an object is full of charges and that object, so the charges, are accelerated, EM radiation is generated during the acceleration.
Isn’t the difference in kinetic energy then equal to the work of the force – the energy emitted during acceleration by the EM radiation?
thank you
Answer
An ordinary object has the same number of positive and negative charges. If the object is accelerated, you could say that each charge emits radiation individually, but the radiation of the positive and negative charges interferes destructively, so nothing is emitted net.
If you accelerate a net charge, it will lose energy by emitting the radiation. You can see this because emitting radiation (just like shooting a projectile) causes a ‘rebound’, so exerts a braking force.
Answered by
Prof Walter Lauriks
Physics Acoustics
Old Market 13 3000 Leuven
https://www.kuleuven.be/
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