Page 12 - Physics - XII

Procedure

1. Clean the ends of the connecting wires with sand paper to remove the insulating coating on them,
if any.
2. Draw the circuit diagram as shown in Fig. 1.1 and according to this diagram arrange the apparatus in
the same manner as shown in Fig. 1.2.
3. While making connections ensure that the +ve marked terminals of voltmeter and milliammeter are
joined towards the +ve terminal of battery.

4. Note the least count and range of voltmeter and milliammeter, and the zero error, if any.
5. Insert the key K, slide the rheostat contact in such a way that the current passing through the wire is
minimum.
6. Note down the reading of voltmeter and milliammeter.

7. Shift the rheostat contact to increase the current. Again note down the readings of voltmeter and
milliammeter.
8. Take at least four more observations for diff erent settings of the rheostat.
9. Cut the resistance wire at the points where it leaves the terminals, stretch it, and fi nd its length by
the metre scale.

10. Record all the observations in the observation table.
11. Repeat steps 1 to 10 for other wires.
+ –

One-way Rheostat
key

Cell (or Battery eliminator)

+ – Resistance wire

+ –
mA

V
Milliammeter

Voltmeter
Fig. 1.2: Arrangement diagram
Observations

1. Least count of metre scale = _____ m

2. Length of the resistance wire, L = _____ m
3. Range of the milliammeter = 0 mA to _____ mA

4. Range of the voltmeter = 0 V to _____ V

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