Samuel Dzifanu
Lab 118: RL Circuits
RL Circuits
Name
: Samuel Dzifanu
Objective:
The objective of this lab was to construct and analyze the current flowing in an RL
Circuit.
Theory:
An inductor is a 2 terminal circuit element that stores energy in its magnetic field. They
are usually constructed by winding a coil with wire.
If a current I is flowing through an inductor, the voltage Vl across the inductor is
proportional to the time rate of change of I or
dIdt
.
=
VL LdIdt
,
where L is the inductance in henries (H). In a series RL circuit with a voltage V(t), the voltage
across the resistor andinductor are designated by Vr and Vl. Moreover Kirchoff’s law, which
states that the voltage changes around the loop is zero, can be written as:
+
=
VL VR V
And assuming Rl =0 and letting
=
VL LdIdt
and Vr = I*R becomes:
+
=
LdIdt RI V
.
Therefore, the solution to the homogenous equation (V(t) = 0 => a short circuit) is
=

It Ioe tLR
, where Io is the current through the circuit at time t=0; and Vl becomes,
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 Spring '11
 Opyrchal
 Physics, Current, Inductance, Energy, Alternating Current, Inductor, RL circuit

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