Page 129 - Science Class 07

There are two types of circuits namely closed
circuit and open circuit.
Closed Circuit
An electric circuit through which an electric
current can flow is called a closed circuit. The
bulb glows in a closed circuit.
Closed Circuit
Open Circuit
An electric circuit through which electric
current cannot flow is called an open circuit.
Open Circuit
You already know that an electric circuit may
consist of conductors, ba ery, switch and other
electrical equipments or devices. To represent
their presence in an electric circuit, it is difficult
as well as awkward to draw their pictures. Look
at the following symbols used in electric
circuits.
+ – + –
Cell Ba ery
Science-7
Switch on Switch off Conduc ng Wire
A V
Lamp Ammeter Voltmeter
Symbols of Some Common Circuit Elements
1. Name the appliances which run on
electricity.
2. What is sta c electricity?
3. Who coined the word electricity?
4. How does electricity flow?
5. Why one end of an electric circuit is
earthed?
6. What is a closed circuit?
7. Name the basic requirements for an
electric circuit.
IMPORTANT DEVICES AND THEIR FUNCTIONS
Let's study about some important devices
which can be a ached in an electric circuit.
Ba ery
It is the source of electric current. Ba eries or
cells must be a ached in a circuit properly. It
means the ends of the ba eries must be in the
same direc on.
Ba eries
v Resistor : It is a device that gives resistance
to electric flow. The filament of the bulb is
also a form of resistor.
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