Which statement best explains why fast-moving electrons slow down when approaching a nucleus?

Which statement best explains why fast-moving electrons slow down when approaching a nucleus?

• A. The nucleus absorbs them completely
• B. They slow due to the strong positive charge of the nucleus
• C. They are repelled by electrons in the beam
• D. They vanish into a different particle

Answer: (C)

The situation hinges on electric forces between charged particles. When a fast-moving electron travels through a region containing other electrons (like in a beam near a nucleus), the repulsive forces from those nearby electrons push against the approaching electron. This push can oppose its forward motion, transferring some of its momentum to the surrounding electrons and slowing it down. In this context, the collective repulsion from electrons in the beam provides the decelerating effect, which is why this statement is considered the best explanation. The nucleus itself being positively charged would attract an isolated electron, which would not slow it in the way described here, and the ideas that the nucleus absorbs the electron or that the electron vanishes into another particle don’t fit the usual interaction in this setup.

The situation hinges on electric forces between charged particles. When a fast-moving electron travels through a region containing other electrons (like in a beam near a nucleus), the repulsive forces from those nearby electrons push against the approaching electron. This push can oppose its forward motion, transferring some of its momentum to the surrounding electrons and slowing it down. In this context, the collective repulsion from electrons in the beam provides the decelerating effect, which is why this statement is considered the best explanation.

The nucleus itself being positively charged would attract an isolated electron, which would not slow it in the way described here, and the ideas that the nucleus absorbs the electron or that the electron vanishes into another particle don’t fit the usual interaction in this setup.