Experiment Description

Experiment

Experiment DL11    Ohm's Law

Objectives
  • Calculate resistance by V-A method using computer interface instead of voltmeter and ammeter.
  • Obtain a plot of voltage against current automatically from a data-logger
  • Learn the differences between ohmic and non-ohmic devices
  • Study the variation of resistance of an incandescent light bulb in an a.c.
Description
In this activity, you will make use of the Power output of the Interface to study variation of current with voltage for a resistor. You won't need any measuring devices or even sensors, because the Interface records both the current and voltage.

In Experiment 1, you will vary the voltage output manually. In each trial, the data is recorded in a table after you press a button. The voltage is plotted against the current by the computer. You will also set a formula to calculate the resistance. The variation of resistance with current is then displayed automatically. You will study the V-I characteristics for both resistor and light bulb filament.

In Experiment 2, you will use the a.c. output of the Interface to study the V-I characteristics again. At very low frequency, you will see the dramatic change in V and I of the light bulb filament.
Apparatus
Science Workshop 750 Interface [1]
resistor (10 ohm) [1]
light bulb 3 V [1]
AC/DC Electronics Lab (alternative) [1]
Experiment