Page 210 - NCERT Science Class 10 English Medium

Figure 12.15
Figure 12.15
Figure 12.15
Figure 12.15 A schematic diagram of one of the common domestic circuits
Figure 12.15
Figure 12.15 gives a schematic diagram of one of the common
domestic circuits. In each separate circuit, different appliances can be
connected across the live and neutral wires. Each appliance has a
separate switch to ‘ON’/‘OFF’ the flow of current through it. In order
that each appliance has equal potential difference, they are connected
parallel to each other.
Electric fuse is an important component of all domestic circuits. We
have already studied the principle and working of a fuse in the previous
chapter (see Section 11.7). A fuse in a circuit prevents damage to the
appliances and the circuit due to overloading. Overloading can occur
when the live wire and the neutral wire come into direct contact. (This
occurs when the insulation of wires is damaged or there is a fault in the
appliance.) In such a situation, the current in the circuit abruptly
increases. This is called short-circuiting. The use of an electric fuse
prevents the electric circuit and the appliance from a possible damage
by stopping the flow of unduly high electric current. The Joule heating
that takes place in the fuse melts it to break the electric circuit.
Overloading can also occur due to an accidental hike in the supply
voltage. Sometimes overloading is caused by connecting too many
appliances to a single socket.

Q U E S T I O N S

1. Name two safety measures commonly used in electric circuits and
appliances.

2. An electric oven of 2 kW power rating is operated in a domestic electric
circuit (220 V) that has a current rating of 5 A. What result do you ?
expect? Explain.
3. What precaution should be taken to avoid the overloading of domestic
electric circuits?

Magnetic Effects of Electric Current 205

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