# Current required in a long wire

• rwilson5
In summary, the question asks for the amplitude of a magnetic field in an electromagnetic wave with a given flux density, as well as the required current to generate the same field at a specific distance from a wire. The relevant equation is provided and the attempt to solve the problem is mentioned, but further guidance is requested.
rwilson5

## Homework Statement

Determine the amplitude of a magnetic field in an electromagnetic wave that carries a flux density of 100 mW/cm2. How much current would be required in a long straight wire so that the magnetic field if this same amplitude would be generated at a distance of 1mm from the wire.

## Homework Equations

$$B_0=\frac{E_0}{c}=\frac{1}{c}\sqrt{\frac{2I}{c\epsilon_0}}$$

## The Attempt at a Solution

I'm not sure how to get at this one. I got that $$B_0=2.89 \cdot 10^{-6} T.$$ Just a touch in the right direction would be awesome.

The approach looks fine, and a computer can check the numerical value. Where is the problem?

## 1. What is the definition of current in a long wire?

The current in a long wire refers to the movement of electric charge or electrons through the wire. It is measured in amperes (A) and is a measure of the amount of charge passing through a given point in the wire per unit of time.

## 2. Why is current required in a long wire?

Current is required in a long wire to allow for the transfer of energy or information. In most cases, the wire is used to connect a power source (such as a battery) to a device, and the current flowing through the wire powers the device. In other cases, the current may carry signals for communication purposes.

## 3. How does the length of a wire affect the required current?

The longer the wire, the higher the required current to achieve the same amount of power or signal transmission. This is because as the length of the wire increases, the resistance to current flow also increases, requiring a higher current to overcome it.

## 4. What factors affect the amount of current required in a long wire?

The amount of current required in a long wire depends on several factors, including the length and thickness of the wire, the material the wire is made of, and the voltage of the power source. These factors affect the wire's resistance, which ultimately determines the required current.

## 5. How can the required current in a long wire be calculated?

The required current in a long wire can be calculated using Ohm's law, which states that current (I) is equal to voltage (V) divided by resistance (R), or I = V/R. The resistance can be calculated using the wire's length, thickness, and material, as well as the specific properties of the material, such as resistivity.

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