# Inductance: Current in terms of Voltage

• a3sportback54
In summary, the conversation is about a problem in electrical engineering involving an inductance with a given current at t=0 and the constant voltage needed to reduce the current to 0A at t=0.4s. The equation and values used are also mentioned, and there is confusion about the correct answer which is determined to be -12V.
a3sportback54
I'm having a bit of trouble getting the right answer for a problem in my electrical engineering textbook. The question is:

At t=0, the current flowing in a 0.6H inductance is 8A. What constant voltage must be applied to reduce the current to 0A at t=0.4s.

I'm using the equation:

$$i(t)=\frac{1}{L}\int\ v(t).dt+i(t_{0})$$ with limits 0.4s and 0s

The answer I'm getting is 12V, and the book says 10V.. which is right??

I'm using L=0.6H, i(t0)=8A, and i(t)=0A

It seems the book answer is wrong. And so is yours. The correct answer would be -12V.

I cannot provide an answer to a specific problem in your textbook. However, I can provide some general information about inductance and its relationship to current and voltage.

Inductance is a property of an electrical circuit that describes how much a circuit resists changes in current. It is measured in units of Henrys (H). Inductors, which are components used in circuits to store energy in the form of a magnetic field, have a specific inductance value.

The relationship between inductance, current, and voltage is described by the equation V=L di/dt, where V is voltage, L is inductance, and di/dt is the rate of change of current over time. This equation is known as Faraday's Law.

In your problem, you are given the inductance value (0.6H) and the initial current (8A) at time t=0. You are also given the final current (0A) at time t=0.4s. To find the constant voltage required to reduce the current to 0A, you can rearrange the equation to solve for V:

V = L di/dt

= (0.6H) [(0A - 8A) / (0.4s - 0s)]

= (0.6H) (-20A/s)

= -12V

Note that the negative sign indicates that the voltage must be in the opposite direction of the initial current to reduce it to 0A.

Therefore, based on the information given in your problem, the answer of 12V is correct. It is possible that there may be a mistake in the book or a typo in the problem. I recommend double-checking your calculations and the given information to determine the correct answer.

## 1. What is inductance?

Inductance is a property of an electrical circuit that describes the ability of the circuit to generate an electromagnetic field when an electrical current flows through it. It is measured in units of Henrys (H) and is denoted by the symbol L.

## 2. How is inductance related to current?

Inductance is directly related to the amount of current flowing through a circuit. When there is a change in the current, there is a corresponding change in the magnetic field produced by the circuit, which in turn affects the inductance.

## 3. What is the relationship between inductance and voltage?

Inductance and voltage are inversely related. This means that as the inductance of a circuit increases, the voltage decreases, and vice versa. This relationship is described by the equation V = L di/dt, where V is the voltage, L is the inductance, and di/dt is the rate of change of current.

## 4. How is inductance calculated?

Inductance can be calculated using the formula L = NΦ/I, where N is the number of turns in the coil, Φ is the magnetic flux, and I is the current. It can also be calculated using the physical dimensions and materials of the circuit, such as the coil length and cross-sectional area.

## 5. What are some applications of inductance?

Inductance has many practical applications in electronics, such as in transformers, motors, and generators. It is also used in electronic filters, antennas, and energy storage devices. Inductors, which are components designed to have high inductance, are commonly used in electronic circuits to control the flow of current and store energy.

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