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物理 · 共 23 題 · 點擊選項即時核對答案

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21.

Two uncharged metal spheres in contact hanging by dry cotton threads with a positively charged rod X nearby

Two uncharged metal spheres in contact are suspended by dry cotton threads. When a positively charged rod $X$ is brought near them as shown above, the distribution of charges on the spheres will be

Four diagrams A to D of charge distributions on two touching spheres

22.

Three metal spheres X, Y, Z in contact, Y earthed, and a negatively charged rod near Z

Three metal spheres $X$ , $Y$ and $Z$ are placed in contact as shown. A negatively charged rod is brought near $Z$ . The sphere $Y$ is then earthed while the charged rod is still nearby. Which of the following statements is/are true ?

(1)

X

is negatively charged.

(2)

Y

is neutral.

(3)

Z

is positively charged.

23.

Two light spheres suspended from silk threads

Two light conducting spheres are suspended from two silk threads as shown. If they are found to attract one another, which one of the following conclusions is/are correct ?

(1)They carry similar charges.

(2)They carry opposite charges.

(3)Only one of them is charged.