Voltage across switch in LR circuit as switch is opened?

In summary, the conversation discusses the change in voltage at the right side of a switch when it is closed and then opened. When the switch is closed, the voltage is expected to be 0, but after it is opened, the voltage becomes εL, which is the induced emf due to the inductor. The voltage across an open switch is given by ε - εL. There is a question about the relationship between resistor R1 and RL and how it affects the voltage across the switch. The conversation ends with a request for clarification on the use of ε and the relationship between current and voltage for an inductor.
  • #1
nikodym
1
0
Moved from a technical forum, so homework template missing
egOw5dN.jpg

1. I thought that when switch was closed, voltage at the right side of switch was 0 and long time after the switch is open, the voltage at the right side of the switch becomes 0.
2. After the switch is open ecause of the inductor, voltage at the right side of the switch is εL = induced emf
So voltage across the open switch = ε -εL

Is there any thing wrong with my thought1 and2?
I don't understand why voltage across the switch becomes greater if R1 is greater than RL.

Thanks for any help in advance:)
 

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  • #2
Hello Nikodym, :welcome:

Hard to read but it looks as if the battery voltage is some kind of ##g##. If the switch is closed for a while, where does that drop to the 0 you expect in step 1 ?

What do you mean with ##\varepsilon## ? Are you aware of the relationship between current and voltage for an induction L ?
 

1. What is the purpose of a switch in an LR circuit?

The switch in an LR circuit serves as a means of controlling the flow of current in the circuit. When the switch is open, no current can flow through the circuit. When the switch is closed, current can flow through the circuit.

2. How does the voltage across a switch in an LR circuit change as the switch is opened?

As the switch in an LR circuit is opened, the voltage across it will initially remain at the same value as before the switch was opened. However, as the current in the circuit decreases, the voltage across the switch will also decrease until it reaches 0V.

3. Why does the voltage across a switch in an LR circuit decrease as the switch is opened?

The voltage across a switch in an LR circuit decreases as the switch is opened because the inductor in the circuit resists changes in current. When the switch is opened, the inductor creates a back EMF (electromotive force) that opposes the decreasing current and causes the voltage across the switch to decrease.

4. What happens to the current in an LR circuit when the switch is opened?

When the switch in an LR circuit is opened, the current in the circuit will decrease over time due to the inductor's back EMF. This decrease in current is known as an exponential decay and it can be described by the equation I(t) = I0*e^(-t/τ), where I0 is the initial current, t is time, and τ is the time constant.

5. How can the voltage across a switch in an LR circuit be calculated?

The voltage across a switch in an LR circuit can be calculated using the equation V = Ldi/dt, where V is the voltage, L is the inductance of the circuit, and di/dt is the rate of change of current. This equation can be used to calculate the voltage at any point in time after the switch is opened, as long as the values for L and di/dt are known.

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