NCERT Book Class 7 Science Chapter 10 Electric Current and its Effects

10 Electric Current
and its Effects

Y
ou might have tried the game 10.1 SYMBOLS OF ELECTRIC
‘How steady is your hand?’ COMPONENTS
suggested in Chapter 9 of Some common electric components can
Class VI. If not, you may try it out now. be represented by symbols. In Table 10.1,
Paheli and Boojho had also set up the some electric components and their
game by connecting an electric circuit symbols are shown. You may come
as suggested in Class VI. They had lots across different symbols for these
of fun trying it out with their families components in different books. However,
and friends. They enjoyed it so much in this book, we shall be using the
that they decided to suggest it to a symbols shown here.
cousin of theirs who stayed in a Look at the symbols carefully. In the
different town. So, Paheli made a neat symbol for the electric cell, notice that
drawing showing how the various there is a longer line and a shorter but
electric components were to be thicker parallel line. Do you recall that
connected (Fig.10.1). an electric cell has a positive terminal
and a negative terminal? In the symbol
of the electric cell, the longer line
represents the positive terminal and the
thicker, shorter line represents the
negative terminal.
For a switch the ‘ON’ position and
the ‘OFF’ position are represented by the
symbols as shown. The wires used to
connect the various components in a
circuit are represented by lines.
In Table 10.1, a battery and its
Fig. 10.1 Setup to check how steady symbol are also shown. Do you know
your hand is what a battery is? Look at the symbol of
a battery. Can you make out what a
Can you draw this circuit battery could be? For some of the
conveniently? It made Boojho wonder if activities we may need more than one
there was an easier way to represent cell. So, we connect two or more cells
these electric components. together as shown in Fig.10.2. Notice