Electric Current and Its effects Class 7 PPT

 Page 1


CHAPTER - 14 
 
Electric current and its effects 
Page 2


CHAPTER - 14 
 
Electric current and its effects 
1) Symbols of electric components :- 
Electric component                                          Symbol 
  i) Electric cell 
 
 ii) Electric bulb  
 
iii) Switch in 
     OFF position   
iv) Switch in 
     ON position  
 
 v) Battery 
 
vi) Wire 
Page 3


CHAPTER - 14 
 
Electric current and its effects 
1) Symbols of electric components :- 
Electric component                                          Symbol 
  i) Electric cell 
 
 ii) Electric bulb  
 
iii) Switch in 
     OFF position   
iv) Switch in 
     ON position  
 
 v) Battery 
 
vi) Wire 
Electric cell :- has a positive terminal and a negative 
terminal. The symbol of an electric cell has a longer line 
and a shorter line. The longer line is the positive terminal 
and the shorter line is the negative terminal. 
Battery :- A battery is a combination of two or more cells. In 
a battery the positive terminal of one cell is connected to 
the negative terminal of another cell. Devices like torches, 
transistors, toys, TV remote controls use batteries. 
   Connecting cells together                          Cell holder 
Page 4


CHAPTER - 14 
 
Electric current and its effects 
1) Symbols of electric components :- 
Electric component                                          Symbol 
  i) Electric cell 
 
 ii) Electric bulb  
 
iii) Switch in 
     OFF position   
iv) Switch in 
     ON position  
 
 v) Battery 
 
vi) Wire 
Electric cell :- has a positive terminal and a negative 
terminal. The symbol of an electric cell has a longer line 
and a shorter line. The longer line is the positive terminal 
and the shorter line is the negative terminal. 
Battery :- A battery is a combination of two or more cells. In 
a battery the positive terminal of one cell is connected to 
the negative terminal of another cell. Devices like torches, 
transistors, toys, TV remote controls use batteries. 
   Connecting cells together                          Cell holder 
2) A simple electric circuit :- 
   A simple electric circuit can be made by using a cell, 
electric bulb, switch and wires. 
  The bulb glows only when the switch is in the ON position 
and the circuit is closed.  
Closed electric circuit 
Open electric circuit 
An electric circuit 
Page 5


CHAPTER - 14 
 
Electric current and its effects 
1) Symbols of electric components :- 
Electric component                                          Symbol 
  i) Electric cell 
 
 ii) Electric bulb  
 
iii) Switch in 
     OFF position   
iv) Switch in 
     ON position  
 
 v) Battery 
 
vi) Wire 
Electric cell :- has a positive terminal and a negative 
terminal. The symbol of an electric cell has a longer line 
and a shorter line. The longer line is the positive terminal 
and the shorter line is the negative terminal. 
Battery :- A battery is a combination of two or more cells. In 
a battery the positive terminal of one cell is connected to 
the negative terminal of another cell. Devices like torches, 
transistors, toys, TV remote controls use batteries. 
   Connecting cells together                          Cell holder 
2) A simple electric circuit :- 
   A simple electric circuit can be made by using a cell, 
electric bulb, switch and wires. 
  The bulb glows only when the switch is in the ON position 
and the circuit is closed.  
Closed electric circuit 
Open electric circuit 
An electric circuit 
3) Heating effect of electric current :- 
    When electric current flows through a wire, the wire gets 
heated. This is called the heating effect of electric current. 
Activity :- 
   Make an electric circuit as shown in the figure. Take a 10 
cm long nichrome wire and tie it between the two nails. 
Switch on the current. After a few seconds touch the wire. 
The wire feels hot. Then switch off the current. After a few 
seconds touch the wire again. It does not feel hot. This 
shows that when electric current flows through a wire, it 
gets heated. 
Nichrome wire 
Nail