4. Complete Activity 10.4 (Page 115). Make the circuit we used for Activity 10.3 again. However, replace the cell with a battery of four cells. Also, in place of the nichrome wire, tie a thin strand of steel wool. If there are any fans in the room, switch them off. Now pass the current through the circuit for sometime. Observe the strand of steel wool carefully. Note what happens. Does the strand of steel wool melt and break?
Answer: Activity 10.4 can be carried out as follows:
Aim: To examine if a high enough current can make the steel wool strand melt and break.
Materials Required: Two iron nails, four electric cells, switch, thin strand of steel wool.
Procedure:
(i)Buy a thin strand of steel wool (used to clean utensils) from the grocery shop and tie it between the two nails.
(ii) Connect it to the switch and the battery of four cells to complete the circuit.
(iii) Switch off any fans in the room and switch on the current.
(iv) Allow the current to pass through the circuit for sometime and carefully observe what happens to the strand of steel wool.
Observations: You will observe that when current is allowed to pass through the circuit for sometime the heating effect of current will melt and break the strand of steel wool.
Conclusions:
- When the high current (battery of four cells) was passed through the strand of steel wool which is very fine and has a low melting point, it heated up due to heating effect of current. This caused it to melt after sometime thereby breaking the circuit.
- This concept of a fine material melting and breaking the circuit when an extremely high current passes through it can be used to protect circuits from damage and fires. This kind of safety device is called a fuse.
“Make the circuit we used for Activity 10.3 again. However, replace the cell with a battery of four cells. Also, in place of the nichrome wire, tie a thin strand of steel wool. If there are any fans in the room, switch them off. Now pass the current through the circuit for sometime. Observe the strand of steel wool carefully. Note what happens. Does the strand of steel wool melt and break?” – Solved.
Related Links:
Solution to Extended Learning Problem 1
Solution to Extended Learning Problem 2
Solution to Extended Learning Problem 3
Solution to Extended Learning Problem 4
Solution to Activity 10.1
Solution to Activity 10.2
Solution to Activity 10.3
Solution to Activity 10.4
Solution to Activity 10.5
Solution to Activity 10.6
