Circuit with Inductor: Current, Battery, Resistor

In summary, the conversation discusses a circuit with a battery, inductor, and resistor in series, and the effects of throwing a switch on the current. It is clarified that the initial current is equal to the battery's emf divided by the resistance, and after the switch is thrown, the inductor provides the only emf in the circuit. The conversation also touches on the oscillatory nature of a circuit with both an inductor and capacitor.
  • #1
wakko101
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The problem is: There is a circuit such that a battery (source of constant emf) is connected to an inductor and a resister (in series). After an unspecified time period, a switch is thrown, effectively bypassing the battery.

I know (becuase I've seen the answer) that a) the initial current is the battery's emf divided by R and b) that once the switch has been thrown, in order to find the current, one would set the emf of the inductor equal to IR (then solved the differential equation). I just want to clarify as to why this is so.

The initial current: the inductor is acting as "back emf" so it's pushing against the current created by the battery. The battery has to do more work in order to maintain the same emf as it would were the inductor not there, however, it doesn't affect that fact that the current is (eventually) equal to the initial emf divided by the resistance. Is that right?

After the switch: the inductor is providing the only emf in the circuit, and it is effectively slowing it down. The potential difference across the resistor will then be equal to the only emf present in the circuit (ie. the inductor).

Does that sound about right?

Another question: why is the current in a circuit consisting of a capacitor at an initial V and an inductor oscillatory? Does that mean it never diminishes, but simply constantly changes direction?
 
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  • #2
The inductor capacitor circuit, commonly called a 'tank circuit' is oscillatory because the inductor charges the capacitor then the capacitor discharges and the current flows back to the inductor then the inductor charges the capacitor again until the current finally decays.
 

What is an inductor?

An inductor is a passive electronic component that is designed to store energy in the form of a magnetic field. It is typically composed of a coil of wire and is used in circuits to control the flow of electrical current.

How does an inductor affect current in a circuit?

When an inductor is placed in a circuit, it resists changes in current flow by storing energy in its magnetic field. This means that when the current in the circuit changes, the inductor will oppose the change and try to maintain a constant current.

What is the role of a battery in a circuit with an inductor?

The battery in a circuit with an inductor serves as the power source. It provides the electrical energy that is stored in the inductor's magnetic field. Without a battery, the inductor would not be able to function.

How do resistors affect the behavior of a circuit with an inductor?

Resistors are used in circuits with inductors to limit the flow of current. This is important because inductors can create large amounts of back EMF (electromotive force) when the current changes, and resistors help to control this effect.

How does the current in a circuit with an inductor change over time?

When a circuit with an inductor is first turned on, the current will increase slowly as the inductor builds up its magnetic field. Once the magnetic field is fully established, the current will reach a steady state. When the circuit is turned off, the current will decrease slowly as the inductor's magnetic field collapses. This behavior of the current is known as inductance.

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