Page 8 - CHAPTER-1 (Electricity)
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CHAPTER 1
ELECTRICITY
(iv) The Flow of Charges Inside a Wire:
• Inside a solid, the atoms are so closely packed together with each
other but electrons are able to travel through the solid crystal as
if they were in vacuum.
• When a steady current flow in a conductor, then the electrons in
it move with a certain average drift speed (the constant speed of
the electrons inside the conductor with which they move under
-4
the effect of external electric supply) of the order of 10 m/s.
• Thus, flow of charges (i.e. electrons) produces a current in a wire.
Ammeter: Electric current is
measured by a device called an
ammeter. It is a low resistance device
which is always connected in series
with a device through which the
current is to be measured.
Fig 4:
Mental floss!
The human body, though has a large resistance of the order of k
(say 10 k), is very sensitive to feeble currents even as low as a few
mA. Electrocuting the body excites and disorders the nervous
system, and hence one fails to control the activity of the body.
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