Page 54 - Physics - XII

10. Insert the plug key K in the circuit and switch ON the battery to read the multimeter reading. Do

not insert any resistance from the resistance box in the circuit. Note the observations and then open
the key K.
11. Next insert a resistance R (≈ 10 Ω) by taking out a resistance plug key from the resistance box. Close
the key K by inserting the plug into it.
12. Read the multimeter reading for measuring the potential diff erence across two ends of the resistor R.
Note the diff erence in the reading when no resistor was connected with the circuit and when a resistor
R is connected.

13. Repeat the steps (11) and (12) three more times with diff erent resistors connected to the battery

Measurement of AC Voltage
14. Connect an A.C. step-down transformer (V = 6 V), a rheostat XY as potential divider, a resistance
out
Box (RB), and a plug key K.
15. Set the multimeter in A.C. voltage measuring mode of the range 0 to 10 V.
16. Connect the free ends of two leads of multimeter to the ends of secondary coil of the transformer, a
potential divider (rheostat) XY, key K, and Resistance Box (RB) setting as shown in the Fig. 2.5.

17. Bring the variable connector Z of the rheostat close to point X, so that the resistance of the rheostat coil
would become minimum.
18. Close the key K and record the multimeter reading for A.C. voltage drop across the resistance R.
19. Repeat the step (17) for atleast three positions of Z of rheostat coil XY.

Measurement of D.C. Current

20. Select the function switch and the range switch/sockets suitable for proper D.C. current measurement.
21. Connect the multimeter in series with the battery, so that the red lead of multimeter is connected to the
positive terminal of the battery and black lead is connected to the negative terminal of the battery.

22. Note the multimeter reading for multimeter set in D.C. current measuring mode.
23. Bring a resistance R in the circuit from the resistance box and close the key K, then note the multimeter
reading for measuring D.C. current fl owing in the circuit.
24. Repeat step (23) for three more values of resistance R.

Digital Multi meter

25. For digital multimeter, the procedure for measuring voltage, current, and resistance is similar to that
of analog measurement. The digital multimeters can accept voltage even with reversed polarities and
display the number when the magnitude of the measured quantity crosses the upper limit of the range
used so that the digital multimeter is not damaged as easily as the analog multimeter.

Observations
1. Range of resistance scale on multimeter panel = 0 to _____ Ω

2. Least count of resistance scale = _____ Ω

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