# Relationship between voltage and current in rl circuit

### RC/RL/LC Circuits | Protocol

In RL Series Circuit the current lags the voltage by degree angle known as the power is negative between angle 0 and ϕ and between degrees and. Electronics Tutorial about the LR Series Circuit with a Series Inductor Resistor ( LR In other words, an inductor in an electrical circuit opposes the flow of current, The voltage drop across the resistor, R is I*R (Ohms Law). The transient time of any inductive circuit is determined by the relationship between the inductance. Describe the relationship between current and voltage in an RL circuit. Determine impedance and phase angle in a series. RL circuit. Analyze a series RL circuit.

In case of pure resistive circuit, the phase angle between voltage and current is zero and in case of pure inductive circuit, phase angle is 90o but when we combine both resistance and inductor, the phase angle of a series RL circuit is between 0o to 90o.

The impedance of series RL Circuit is nothing but the combine effect of resistance R and inductive reactance XL of the circuit as a whole. Series RL Circuit Analysis In series RL circuit, the values of frequency f, voltage V, resistance R and inductance L are known and there is no instrument for directly measuring the value of inductive reactance and impedance; so, for complete analysis of series RL circuit, follow these simple steps: Since the value of frequency and inductor are known, so firstly calculate the value of inductive reactance XL: From the value of XL and R, calculate the total impedance of the circuit which is given by Step 3.

Since the resistor and the inductor are connected in series, so current in them remains the same. The rate at which energy is stored in inductor, So, total power in series RL circuit is given by adding the power dissipated by the resistor and the power absorbed by the inductor.

### Series Resistor-Inductor Circuits | Reactance and Impedance -- Inductive | Electronics Textbook

As with the purely inductive circuit, the current wave lags behind the voltage wave of the sourcealthough this time the lag is not as great: Figure below Current lags voltage in a series L-R circuit.

We can verify this mathematically: The voltage across the resistor has the exact same phase angle as the current through it, telling us that E and I are in phase for the resistor only.

The voltage across the inductor has a phase angle of This tells us that E and I are still 90o out of phase for the inductor only. Figure below Spice circuit: Instead of a phase angle of This is merely an idiosyncrasy of SPICE and does not represent anything significant in the circuit simulation itself.

Note how both the resistor and inductor voltage phase readings match our calculations Applying a table to this simple series resistor-inductor circuit would proceed as such. If you are using a calculator that has the ability to perform complex arithmetic without the need for conversion between rectangular and polar forms, then this extra documentation is completely unnecessary. Since this is a series circuit, we know that opposition to electron flow resistance or impedance adds to form the total opposition: Just as with DC, the total current in a series AC circuit is shared equally by all components.

Obtain an oscilloscope, a small light bulb with a resistance of a few ohms, a switch and a DC voltage supply or 1. Assemble this circuit and leave the switch open. Select the vertical scale of the oscilloscope to 1 volt per division and the time scale to 1 second per division.

## RC/RL/LC Circuits

Later it may be necessary to adjust these settings for optimal viewing of signals during the various tests. Close the switch to apply power to the light bulb. Because the light bulb acts like a resistor, the current through it is proportional to voltage. As the oscilloscope traces show, the bulb brightens instantly when the switch closes and darkens instantly when the switch opens. Assemble the circuit as shown with a 1 Farad capacitor in series with the light bulb.

Note that the oscilloscope measures voltage across the resistor. Leave the switch open until the start of the test. Close the switch and observe the light bulb and the oscilloscope trace. The light bulb glows briefly before darkening because the capacitor passes current when the voltage changes suddenly, when the switch closes. As time progresses, the current through the circuit decays due to the light bulb resistance and the capacitance. Open the switch and modify the circuit by connecting a second light bulb in parallel with the first.

**Electrical Engineering: Ch 8: RC & RL Circuits (14 of 43) Current=? in RL Circuit: Ex. 2**

Again close the switch. Watch both light bulbs and the oscilloscope trace. The two parallel bulbs turn on and off more quickly than the single bulb. This is because the parallel resistance of two bulbs is smaller than the resistance of a single bulb. The resulting circuit has a shorter drop in the current and a faster response. Assemble this circuit with a 1 milli Henry inductor in series with the light bulb. The light bulb takes a small amount of time to turn on because the inductor conducts little current when the voltage changes suddenly, as when the switch closes.

As time progresses, the inductor's current-and that through the bulb-approaches a steady state level. Open the switch and connect a second light bulb in parallel with the first. The two parallel bulbs turn on and off more slowly than the single bulb. Assemble this circuit with a 10 micro Farad capacitor, and an 8 milli Henry inductor, along with the oscilloscope connected across the capacitor.

Open switch 1 to disconnect the voltage source from the circuit. Close switch 2 and observe the oscilloscope. The inductor voltage oscillates and may show some damping caused by the small resistance of the wires in the circuit. The period of oscillation is on the order of milli seconds, which is consistent with the expected time based on the values of capacitance and resistance. Resistors, capacitors and inductors are simple components but the RC, RL and LC circuits that use them have complex behaviors, which enable many applications in electronic signal processing, timing circuits, and filters.

In this example, researchers implanted subcutaneous radio transmitters in mice to study blood pressure as they moved freely. Radio receivers commonly use inductor-capacitor circuits to select a specific frequency from the broad band of intercepted radiofrequency, or RF, energy.

- RL circuit
- RL Series Circuit
- Series Resistor-Inductor Circuits

The correct frequency carries the desired information for amplification and further processing by additional electronics in the receiver. Electroencephalographs measure electrical activity in the brain. Electrodes placed over the scalp pick up millivolt level signals over a wide frequency range. RC, RL, and LC circuits are part of the filters that reduce electrical interference and artefacts, thus helping in acquisition of meaningful data.

You've just watched JoVE's introduction to the time dependent behavior of circuits using resistors, capacitors and inductors. Results For step 1, the light bulb will "instantly" turn on and off when closing step 1.

Representative oscilloscope traces are shown in Figure 8. When two parallel light bulbs are used step 2. Representative traces on the oscilloscope for the two cases are shown in Figure 9.

When two parallel light bulbs are used step 3. Representative traces on the oscilloscope for the two cases are shown in Figure Some damping of the oscillation may be observed due to the finite resistance of the wires connecting the circuit. Representative oscilloscope traces or "waveforms" that may be observed in the experiment depicted in Figure 4, when the switch is closed or opened, measuring the voltage across a light bulb directly connected to a voltage supply.

Representative oscilloscope traces or "waveforms" that may be observed when the switch is closed in the experiment depicted in Figure 5, measuring the voltage across a light bulb connected in series of an inductor and a voltage supply.

Representative oscilloscope traces or "waveforms" that may be observed when the switch is closed in the experiment depicted in Figure 6, measuring the voltage across a light bulb connected in series of a capacitor and a voltage supply Applications and Summary In this experiment, we have demonstrated the time dependent response exponential turning on and off in RC or RL circuits, and how changing the resistance affects the time constant.