Page 72 - Physics 10_Float

ELECTROSTATICS

Detecting the Presence of Charge
In order to detect the presence of charge on anybody, bring
the body near the disk of an uncharged electroscope. If the
body is neutral there will be no deflection of the leaves
(Fig.13.7-a). But if the body is positively or negatively
charged, the leaves of the electroscope diverge. For example,
if the body is negatively charged then due to electrostatic
induction, positive charge will appear on the disk while (a)
negative charge will appear on the leaves (Fig.13.7-b). The
leaves of electroscope repel each other and diverge because
each leave gets similar charge. The divergence of leaves will
depend on the amount of charge.

Charging the Electroscope by Electrostatic Induction
Electroscope can be charged by the process of
electrostatic induction. In order to produce positive
charge on the electroscope, bring a negatively charged
body near the disk of the electroscope (Fig.13.8-a). (b)
Positive charge will appear on the disk of the electroscope
while negative charges will shift to the leaves. Now Fig. 13.7
connect the disk of electroscope to the earthed
aluminium foil by a conducting wire (Fig. 13.8-b). Charge
of the leaves will flow to the Earth through the wire. Now
if we first break the Earth connection and then remove the
rod, the electroscope will be left with positive
charge(Fig.13.8-c) .

Electrons
flow
to the
Earth

Fig.13.8 (b) Charging the Fig.13.8 (c) Positively charged
Fig.13.8 (a) Charging the electroscope
electroscope positively electroscope positively

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