Page 209 - NCERT Science Class 10 English Medium

2. In Activity 12.7, how do we think the displacement of rod AB will be
affected if (i) current in rod AB is increased; (ii) a stronger horse-shoe
magnet is used; and (iii) length of the rod AB is increased?
3. A positively-charged particle (alpha-particle) projected towards west is
deflected towards north by a magnetic field. The direction of magnetic
field is
(a) towards south (b) towards east
(c) downward (d) upward

More to Know! An electric current always produces a magnetic field. Even weak ion currents that
Magnetism in medicine

travel along the nerve cells in our body produce magnetic fields. When we touch
something, our nerves carry an electric impulse to the muscles we need to use. This
impulse produces a temporary magnetic field. These fields are very weak and are
about one-billionth of the earth’s magnetic field. Two main organs in the human
body where the magnetic field produced is significant, are the heart and the brain. The
magnetic field inside the body forms the basis of obtaining the images of different body
parts. This is done using a technique called Magnetic Resonance Imaging (MRI). Analysis
of these images helps in medical diagnosis. Magnetism has, thus, got important uses
in medicine.

12.4
12.4 DOMESTIC ELECTRIC CIRCUITSDOMESTIC ELECTRIC CIRCUITS
ELECTRIC
CIRCUITS
DOMESTIC ELECTRIC CIRCUITS
12.4 DOMESTIC ELECTRIC CIRCUITS
12.4
12.4 DOMESTIC
In our homes, we receive supply of electric power through a main supply
(also called mains), either supported through overhead electric poles or
by underground cables. One of the wires in this supply, usually with
red insulation cover, is called live wire (or positive). Another wire, with
black insulation, is called neutral wire (or negative). In our country, the
potential difference between the two is 220 V.
At the meter-board in the house, these wires pass into an electricity
meter through a main fuse. Through the main switch they are connected
to the line wires in the house. These wires supply electricity to separate
circuits within the house. Often, two separate circuits are used, one of
15 A current rating for appliances with higher power ratings such as
geysers, air coolers, etc. The other circuit is of 5 A current rating for
bulbs, fans, etc. The earth wire, which has insulation of green colour, is
usually connected to a metal plate deep in the earth near the house.
This is used as a safety measure, especially for those appliances that
have a metallic body, for example, electric press, toaster, table fan,
refrigerator, etc. The metallic body is connected to the earth wire, which
provides a low-resistance conducting path for the current. Thus, it
ensures that any leakage of current to the metallic body of the appliance
keeps its potential to that of the earth, and the user may not get a severe
electric shock.

204 Science

2024-25