# Electricity | Activities in Text Book with Solution

Activity 12.3

Complete an electric circuit consisting of a cell, an ammeter, a nichrome wire of length [say, marked (1)] and a plug key, as shown in Fig. 12.5.

Now, plug the key. Note the current in the ammeter.

✅ Answer: Let's assume the current in the ammeter is 1 A.

Replace the nichrome wire by another nichrome wire of same thickness but twice the length, that is 2l [marked (2) in the Fig. 12.5]. Note the ammeter reading.

Now replace the wire by a thicker nichrome wire, of the same length l [marked (3)]. A thicker wire has a larger cross-sectional area. Again note down the current through the circuit.

Answer: Here, reading is increased. If the cross-sectional area is doubled, the ammeter reading is also doubled (2 A).

Instead of taking a nichrome wire, connect a copper wire [marked (4) in Fig. 12.5] in the circuit. Let the wire be of the same length and same area of cross-section as that of the first nichrome wire [marked (1)]. Note the value of the current.

Notice the difference in the current in all cases.

Does the current depend on the length of the conductor?