PASCO EM-8656 AC_DC ELECTRONICS LABORATORY - Manual (Page 52)

48
AC/DC Electronics Laboratory 012-05892A
®
➃
Subtract the time for the peak voltage from the time for the half-max voltage to get the time for the
voltage to reach half-max. Record this time in the Data Table.
➄
Based on the total resistance in the circuit and the stated value for the inductance of the inductor
coil (8.2 millihenry or 0.0082 mH), calculate
τ =
L
R
.
Data Table
Inductor Resistance
Ω
Resistor Resistance
Ω
Peak Voltage (for Resistor) V
Time at Peak Voltage sec
Time at Half-Maximum Voltage sec
Time to reach Half-Maximum sec
τ
= L/R
Questions
➀
How does the inductive time constant found in this experiment compare to the theoretical value
given by t = L/R? (Remember that R is the total resistance of the circuit and therefore must
include the resistance of the coil as well as the resistance of the resistor.)
➀
Does Kirchhoff’s Loop Rule hold at all times? Use the graphs to check it for at least three different
times: Does the sum of the voltages across the resistor and the inductor equal the source voltage at
any given time?
Extension
Place the iron core in the coil and repeat “Part III: Data Recording”. From the relationship
τ =
L
R
and t
1/2
=
τ
ln(2) find the new value of the inductor.