Section 14.1 Electrostatic Phenomena

Section 14.1 Electrostatic phenomena • Like charges and unlike charges

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14.1 Electrostatic phenomena (SB p. 4)

Electrostatic phenomena The hair was attracted by a plastic comb

The hand got an electric shock

A crackling sound is heard

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Quiz

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Activity 1

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14.1 Electrostatic phenomena (SB p. 4)

Electrostatic phenomena In dry days • many experiences due to static charges ⇒ electrostatic phenomena • For example Screen of TV becomes dusty → static charges accumulate → attract dust particles in air Thinking 1 © Manhattan Press (H.K.) Ltd.

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14.1 Electrostatic phenomena (SB p. 5)

Like charges and unlike charges

Two acetate strips: like charges repel Two polythene strips: like charges repel © Manhattan Press (H.K.) Ltd.

Two strips that carry unlike charges attract 4

14.1 Electrostatic phenomena (SB p. 5)

Like charges and unlike charges Two kinds of charge • positive charge • negative charge like charges repel

unlike charges attract

Some objects are rubbed → objects become electrically charged → exert forces on others © Manhattan Press (H.K.) Ltd.

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To section 14.2

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14.1 Electrostatic phenomena (SB p. 2)

Quiz

1. In dry day, you may hear a crackling sound while combing your hair with a plastic comb. What should you do to avoid producing the crackling sound? Answe B. Use a metal comb. r © Manhattan Press (H.K.) Ltd.

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14.1 Electrostatic phenomena (SB p. 2)

Quiz (Cont)

2. When lightning occurs, which of the following umbrellas should you use? C. The umbrella with a wooden frameAns wer © Manhattan Press (H.K.) Ltd.

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14.1 Electrostatic phenomena (SB p. 2)

Quiz (Cont)

3. Which of the following statements is Ans correct? wer B. Two positive charges repel. Return to © Manhattan Press (H.K.) Ltd.

Text

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14.1 Electrostatic phenomena (SB p. 3)

Activity 1 Rubbing balloon

Let’s start:

Fig. (a)

1. Hold a dry rubber balloon and rub it gently with a woollen cloth (Fig. (a)). 2. Place the balloon close to your classmate’s hair. What happens? The hair is attracted by the balloon. © Manhattan Press (H.K.) Ltd.

Ans wer 10

14.1 Electrostatic phenomena (SB p. 4)

Activity 1 (Cont) Rubbing balloon Fig. (b)

3. Turn on a water tap until the water flows out as a thin stream. 4. Place the balloon near the stream of running water (Fig. (b)). What happens? Ans The stream of running water bends wer towards the balloon. © Manhattan Press (H.K.) Ltd.

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14.1 Electrostatic phenomena (SB p. 4)

Activity 1 (Cont) Rubbing balloon

5. Repeat steps 1 to 4 with a wet balloon. What happens? Why? They are not attracted by the balloon Ans because it is difficult to charge a wet werReturn to balloon. Text © Manhattan Press (H.K.) Ltd.

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14.1 Electrostatic phenomena (SB p. 4)

Thinking 1

List some products or devices that may eliminate the effect of electrostatic Ans nuisance. wer

Monitor filter, hand cream and floor wiper

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