Page 151 - Science Class 08

i The nuclear of an atom has neutrons and protons, they are called nucleons.
i The nucleus is surrounded by electrons.

i Protons are positively charged and electrons are negatively charged and neutrons have no
charge.
i When an atom gains an extra electron, it becomes negatively charged and if it losses an
electron, it becomes positively charged. It is because an atom has equal number of electrons
and protons.
i A neutral body can be charged by conduction or by induction.
i Electroscope is a simple instrument which is used to know whether a body is charged or not.

i The electricity that travels along wires is electricity in motion or current electricity.
i Benjamin Franklin first proved that clouds build up charge during a thunderstorm.

i A lightning conductor is a simple device that is used to protect structures from the harm of
lightning.

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A. Tick (3) the correct op on.
1. Who first discovered about sta c electricity?
(a) Newton (b) Benjamin Frankline
(c) Aryabha a (d) Charles Babbag
2. If we bring electrified glass rod and silk cloth closer, they will:
(a) repel each other (b) a ract each other

(c) become neutral (d) none of these
3. A posi vely charged object is one which has less number of electrons than _____ protons.
(a) less (b) more
(c) equal (d) none of these

4. Which of the following is not a conductor?
(a) Silver (b) Iron
(c) Plas c (d) Gold
5. Where is lightning conductor set in the buildings?

(a) At the base (b) On the roof
(c) In the room (d) In the center
B. Fill in the blanks.

1. The electricity that travels along wire is electricity in _____________________ .

2. The nucleus is surrounded by _____________________ .
3. Ma er as a whole is ordinarily electrically _____________________ .

Science-8 151