Welcome to Physics Problems Q&A, where you can ask questions and receive answers from other members of the community.

Problem 5.13 Griffiths; Balancing magnetic attraction with electrical repulsion

1 vote

I do not get why it is argued that the balancing is impossible; in fact, we are working with line charges, which do travel at the speed of light.

asked 6 days ago in Physics Problems by Jorge Daniel (578 points)

1 Answer

1 vote
Best answer

The line charges must have some mass. Because of this it is impossible to accelerate them to the speed of light.

Increasing their speed also increases their inertia. Initially almost all of the work done increases their speed and almost none increases their inertia. As their speed approaches the speed of light, almost all of the work done on them increases their inertia and there is little increase in speed.

So their speed will always be less than the speed of light, although you can get as close to $c$ as you wish.

answered 6 days ago by sammy gerbil (27,556 points)
edited 6 days ago by sammy gerbil