7
QuizMultiple Choice

Modern Physics — Test

Question 7 • Physics

What is the best explanation for why a particle is striking point X?

Answer
A
If an alpha particle hits the gold foil, a gold nucleus splits and a particle from it flies out at point X.
B
The gold atoms contain negative electrons, so when alpha particles strike the gold they keep moving but in various directions.
C
Alpha particles are mostly empty space, so they move in random directions, and one of these alpha particles can strike point X.
D
When the dense, positive alpha particle passes close to a positive nucleus of gold, the alpha particle repels and hits the screen at point X.

Explanation

Alpha particles and gold nuclei are both positively charged, so they repel each other. An alpha particle passing close to a gold nucleus is deflected from its original path and may strike the screen at point X. The gold nucleus does not split, as choice D suggests.

AI-written and checked against the verified answer.

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