Name: rl circuit and frog leg current response
Uploaded: 2024-04-11T12:48:44.000Z
Duration: 1 min 14 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Specialised Topic in Science

112.51.c.1.

112.51.c.2.D.

Design Example: Frog Muscle Response

Uczeń wykorzystuje obwód RL do badania reakcji mięśni nogi żaby na stymulację elektryczną.
Zamknięcie przełącznika powoduje krótki skurcz mięśni, podczas gdy otwarcie go wyzwala ciągłą aktywność mięśni przez 0,01 sekundy.
Uczeń modeluje żabią nogę jako rezystor, aby określić jej rezystancję, zakładając, że prąd o natężeniu 20 miliamperów indukuje trwałą odpowiedź mięśni.
Gdy przełącznik jest zamknięty, cewka indukcyjna działa jak zwarcie w stanie ustalonym, omijając rezystor i powodując łagodny skurcz mięśni.
Zastosowanie prawa Ohma do rezystora 60 omów daje prąd początkowy.
Po otwarciu przełącznika obwód staje się obwodem RL bez źródła. Prąd przepływa teraz przez rezystor, powodując ciągłą aktywność mięśni.
Stała czasowa jest równa stosunkowi indukcyjności do rezystancji, a prąd przepływający przez cewkę indukcyjną jest wyrażony za pomocą obliczonego prądu początkowego i stałej czasowej.
Wartości prądu i czasu odpowiadające utrzymującej się aktywności mięśni są podstawiane do bieżącego równania. Rozwiązanie równania daje wartość nieznanego oporu.

przykład projektu: reakcja mięśni żaby

Student otrzymuje zadanie opracowanie eksperymentu z udziałem obwodu RL (rezystor-induktor) w celu zbadania reakcji mięśni żabiej nogi na stymulację elektryczną. Obwód RL odgrywa kluczową rolę w tym eksperymencie, zapewniając środki do kontrolowania i pomiaru impulsów elektrycznych wywołujących skurcz mięśni.

Kiedy przełącznik łączący obwód RL jest zamknięty, obserwuje się krótkotrwały skurcz mięśnia. Dzieje się tak, ponieważ w stanie ustalonym cewka indukcyjna działa jak zwarcie, omijając rezystor i powodując łagodny, krótki skurcz żabiej nogi. Stosując prawo Ohma do rezystora 60 omów, student może obliczyć początkowy prąd przepływający przez obwód.

Po otwarciu przełącznika obwód RL staje się wolny od źródła. Teraz prąd przepływa przez rezystor, który student modeluje jako nogę żaby. Zmiana ta powoduje utrzymującą się aktywność mięśniową trwającą przez dziesięć sekund.

Student zakłada, że za wywołanie tej trwałej reakcji mięśni odpowiedzialny jest prąd o natężeniu 20 miliamperów. Aby zweryfikować to założenie, używa stałej czasowej obwodu RL, która równa się stosunkowi indukcyjności do rezystancji. Prąd płynący przez cewkę indukcyjną można wyrazić, używając obliczonego początkowego prądu oraz tej stałej czasowej.

Podstawiając wartości prądu i czasu odpowiadające utrzymującej się aktywności mięśniowej do równania prądu, student może obliczyć nieznaną rezystancję. Ta wartość rezystancji reprezentuje modelowaną rezystancję nogi żaby.

Eksperyment ten stanowi praktyczną demonstrację tego, jak obwody RL mogą być używane do badania odpowiedzi fizjologicznych. Ilustruje podstawowe zasady rządzące tymi obwodami, takie jak odpowiedzi przejściowe i ustalone, oraz pojęcie stałej czasowej. Porównując obwody elektryczne i systemy biologiczne, pokazuje również interdyscyplinarny charakter nauki, łącząc fizykę i biologię.

Przykład projektu: reakcja mięśni żaby

Uczeń wykorzystuje obwód RL do badania reakcji mięśni nogi żaby na stymulację elektryczną.
Zamknięcie przełącznika powoduje krótkotrwały mięsień...

Education

JoVE Core

Electrical Engineering

Elektrotechnika

Unit 1

Jednostka 1

First and Second-Order Circuits

Obwody pierwszego i drugiego rzędu

KEY TERMS AND CONCEPTS

KLUCZOWE TERMINY I POJĘCIA

rl circuit and frog leg current response

An RL circuit is used to model the frog leg’s response to electrical stimulation. In this setup, the student studies how current changes in a resistor-inductor circuit can trigger muscle contraction. The circuit provides a way to control and measure the electrical impulses involved in the experiment.

When the switch is closed, the frog’s leg shows a brief contraction. At steady state, the inductor acts like a short circuit. That lets current bypass the resistor and produces a mild, short muscle response. The student uses Ohm’s law with the 60-ohm resistor to find the initial current in the circuit.

When the switch is opened, the RL circuit becomes source-free. The current then flows through the resistor, which is modeled as the frog’s leg. This change leads to sustained muscle activity that lasts for ten seconds. The student assumes that 20 milliamperes is the current needed for this response.

To test that assumption, the student uses the RL time constant. The time constant is the inductance divided by the resistance. The current in the inductor is written using the initial current and this time constant. By substituting the current and time values for the sustained muscle activity, the student solves for the unknown resistance. That value represents the modeled resistance of the frog’s leg.

This experiment shows how RL circuits can be used to study physiological responses. It also connects transient and steady-state behavior with the idea of a time constant. By linking physics and biology, the setup shows how electrical circuit ideas can help explain a living system.

RL Circuit and Frog Leg Current Response

first-order circuits

First-Order Circuits in Flashing Lamps

First-order circuits use a resistor and one energy storage element, either a capacitor or an inductor. They are common in electronic systems and are described by a first-order differential equation that links the input and output signals. One important example is the RC circuit, which uses a resistor and a capacitor. In a relaxation oscillator such as a neon lamp circuit, the capacitor starts charging when voltage is applied. At first, the lamp behaves like an open circuit. When the capacitor...

rc circuit without source

RC Capacitor Discharge After Power Loss

An RC circuit discharges after the DC source is removed. If the capacitor was fully charged first, its initial voltage, V0, provides the energy that drives the source-free circuit. Kirchhoff’s current law is applied at the top node of the circuit. The current terms for the resistor and capacitor are then substituted, which leads to a first-order differential equation. Rearranging, integrating, and taking the exponential gives the natural response of the circuit. The integration constant in...

rc circuit with source

RC Circuit Charging After a DC Step

An RC circuit with a DC source shows how a capacitor charges after a sudden voltage step. The applied source is treated as a unit step function, and the capacitor voltage is the step response of the circuit. This response describes how the circuit reacts right after the input changes. A capacitor cannot change its voltage instantly. So, immediately after the switch closes at t=0, the capacitor voltage stays at its initial value. Kirchhoff’s current law is then applied at that moment and...

rl circuit without source

RL Circuit Decay After Source Removal

An RL circuit begins to decay after the DC source is removed. At that moment, the circuit becomes source-free. If the inductor has an initial current, I0, it also stores initial energy. That stored energy drives the natural response of the circuit. Kirchhoff’s voltage law is applied around the loop. The inductor voltage and resistor voltage are substituted into the equation. This gives a first-order differential equation for the current. Rearranging the terms produces a logarithmic form, which...

rl circuit with source

RL Step Response Under a DC Source

An RL circuit connected to a DC source has a step response that changes over time. The response has two parts: the transient response and the steady-state response. The transient response is the short-lived reaction that happens right after the source is applied. During the transient phase, the current changes exponentially. If the circuit starts with current in the inductor, that current decays toward zero as time goes on. At this stage, the inductor acts like a short circuit, so the source...

design example: frog muscle response

An RL circuit is used to model the frog leg’s response to electrical stimulation. In this setup, the student studies how current changes in a resistor-inductor circuit can trigger muscle contraction. The circuit provides a way to control and measure the electrical impulses involved in the experiment. When the switch is closed, the frog’s leg shows a brief contraction. At steady state, the inductor acts like a short circuit. That lets current bypass the resistor and produces a mild, short...

second-order circuits

RLC Damping and Resonant Frequency

Second-order circuits use two energy storage elements, such as a capacitor and an inductor, to shape how current and voltage change over time. These circuits include RLC circuits, along with RC and RL circuits that have two capacitors or two inductors. Their behavior is described by second-order differential equations that connect the input signal to the output signal. The input usually comes from a voltage source or a current source. The output is often the voltage across the capacitor, the...

series rlc circuit without source

Natural Response of a Source-Free RLC Circuit

A source-free RLC circuit is a series circuit with a resistor, inductor, and capacitor, but no external energy source. It begins with the energy already stored in the capacitor and inductor. That stored energy drives the circuit at first. The circuit is described by a second-order differential equation. This equation shows how the resistor, inductor, and capacitor interact over time. The resistor removes energy from the circuit, so the solution has an exponential form. When the exponential...

types of responses of series rlc circuits

types-of-responses-of-series-rlc-circuits

Damping in Series RLC Circuit Responses

A source-free series RLC circuit shows three response patterns based on damping. The circuit is described by a second-order differential equation. Its complete solution is made from two distinct solutions. Those solutions depend on the roots, which are written in terms of the damping factor and the resonant frequency. When the damping factor is greater than the resonant frequency, both roots are real and negative. This gives an overdamped response. The circuit output decays slowly over time. <br...

series rlc circuit with source

Forced Response in a Series RLC Circuit

A series RLC circuit with a DC source can model an automobile ignition system. The circuit shows how a battery can produce the high voltage needed for a spark. In this case, the input DC voltage acts like a forcing step function. Applying Kirchhoff's voltage law leads to a second-order differential equation. A second-order differential equation is an equation with a term for the second derivative. The form of this equation is very similar to the one used for a source-free RLC circuit, so the...

parallel rlc circuits

Parallel RLC Step Response in Surge Protectors

Parallel RLC circuits help explain how a surge protector works in a street lamp. The circuit model uses a DC input source that creates a step response when the switch is turned on. This setup shows how the lamp’s components can be protected from sudden voltage spikes. When the switch closes, Kirchhoff’s current law is applied to the parallel RLC circuit. That leads to a second-order differential equation. The solution has two parts: a transient response and a steady-state response. The...

second-order op amp circuits

Second-Order Op Amp Low-Pass Filters

Second-order op-amp low-pass filters remove unwanted high-frequency noise from audio signals. They are used in audio systems to refine sound quality. These filters are often built as voltage followers and have two nodes with storage elements. The circuit analysis follows the same basic method used for second-order RLC circuits. In practice, bulky inductors are usually avoided because of their size and weight. For that reason, the focus here is on RC second-order op-amp circuits, which are...

design example: underdamped parallel rlc circuit

design-example-underdamped-parallel-rlc-circuit

Oscillator Design with a Parallel RLC Circuit

A parallel RLC circuit can be designed to work as an oscillator with underdamped behavior. This example targets a damped natural frequency of 4 kHz and a damping factor of 4 radians per second. A fixed resistance of 200 Ω is used as the starting point for the design. The first step is to find the capacitance. The damping factor is the reciprocal of twice the product of resistance and capacitance. Using that relationship, the needed capacitance value can be calculated from the given resistance...

key terms and concepts

Explore how an RL circuit models frog leg muscle response, from brief contraction to sustained activity, using current, time constant, and resistance.

RL Circuit and Frog Leg Current Response | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

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Deductive Reasoning

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Correlation and Causation

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Ask questions and define problems related to specialized topics of study based on observations or information from text, phenomena, models, or investigations;

112.51.c.1.A.

Scientific Method

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Demonstrating the Scientific Method with Tree Branches
ExpandObtain branches containing a few dozen typical leaves from five different local tree species. ...

Observation and Background Research
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Problem Definition

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Apply science practices related to specialized topics of study to plan and conduct investigations or use engineering practices to design solutions to problems;

112.51.c.1.B.

Proper Personal Protective Equipment

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Proper Waste Disposal

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112.51.c.1.C.

Common Lab Glassware and Uses

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112.51.c.1.D.

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Measurement: Standard Units

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Measurement: Derived Units

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Collect quantitative data using the International System of Units (SI) or qualitative data as evidence as appropriate to the specialized topic of study;

112.51.c.1.E.

Review and Preview

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Ogive Graph

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Relative Frequency Histogram

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Scatter Plot

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112.51.c.1.F.

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112.51.c.1.G.

Scientific Laws and Theories

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Distinguish among scientific hypotheses, theories, and laws as appropriate to the specialized topic of study.

112.51.c.1.H.

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112.51.c.2.A.

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RL Circuit and Frog Leg Current Response

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