Measurement of the Resistivity of the Material of a Wire Apparatus Nichrome wire, micrometer, ohmmeter, leads and crocodile clips, metre stick
RECORD MAX MIN 0 1 234567890
DIGITAL MULTIMETER 25.7
MINMAX HZ mV
Procedure Make a note of the zero error on the micrometer.
Measure the diameter at different points along the wire, using the micrometer.
Subtract the zero error on each occasion. Measure the resistance of the leads when the crocodile clips are connected together, using the ohmmeter.
Set up apparatus as illustrated in Fig 18.17, stretching the wire so as to remove any kinks or slack in it.
Measure the distance (l) between the crocodile clips, using the metre stick.
10 20 30 40 50 Fig 18.17
Measure the resistance of the leads plus the resistance of wire between the crocodile clips, using the ohmmeter. Subtract the resistance of the leads to get the resistance (R) of the wire.
Decrease the distance between the crocodile clips and repeat the process so as to get six or seven readings.
Calculations Calculate the average value for the diameter (d). Calculate the value for for each value of l using the formula Calculate the average value for .r
