# Magnetic fields around electric current

• chris_yau
In summary, the conversation discussed an experiment on magnetic fields around electric current in a straight wire using a search coil. It was necessary to ensure that the search coil was at the same level as the wire in order to obtain accurate measurements of induced e.m.f. The sensitivity of the search coil could be increased by increasing the frequency, as this would result in a higher induced e.m.f. and therefore greater sensitivity. However, the participant did not observe an actual increase in sensitivity and suggested that it could be due to losses in the primary and secondary coils if there was ferrite or iron connecting them.
chris_yau
I have just done an experiment of magnetic fields around electric current in straight wire by using the seach coil.

(1)why is this necessary to ensure the search coil is at the same level as the wire?
My anwser:If the seach coil is not at the same level as the wire, the measurement is not correct. It is because the induced e.m.f. is the greatest around the wire. We should put the seach coil at the same level to have a clear measurement of induced e.m.f.

(2)why the sensitivity of the seach coil can be increased by increasing the frequency?
My anwser:If the frequency increased, the current changed its direction more frequently. Thus, the induced e.m.f will increase. As a result, the seach coil had a increase in sensitivity.

Am I correct??

-1- is okay, but -2- is not quite right, I don't think. Did you actually see an increase in output voltage amplitude of the sense coil for higher primary coil drive frequencies? Was the primary coil drive voltage amplitude changing as well, or was it steady?

To be frank, it is the question in the report.
Actually, I didn't see the increase of the sensitivity.

The only effect that I can think of that would make someone think there was increased sensitivity is if the drive circuit for the primary coil couldn't drive the low inductance of the coil at low frequencies. But the transfer function between the primary and secondary coils should not vary with frequency. If there is ferrite or iron or something connecting the primary and secondary, you will get losses that depend on the material.

## What is a magnetic field?

A magnetic field is a region in space where magnetic forces can be detected. It is created by moving electric charges, such as in an electric current.

## How does an electric current create a magnetic field?

An electric current is a flow of electric charges, and these moving charges create a magnetic field around them. The strength of the magnetic field is determined by the amount of current and the distance from the current.

## What is the shape of a magnetic field around an electric current?

The shape of a magnetic field around an electric current is circular, with the current running through the center of the circle. The direction of the magnetic field is determined by the direction of the current, following the right-hand rule.

## Can the strength of a magnetic field be changed?

Yes, the strength of a magnetic field can be changed by changing the amount of current or the distance from the current. It can also be changed by using materials that can be magnetized, such as iron, which can enhance the magnetic field.

## What are the practical applications of magnetic fields around electric currents?

Magnetic fields around electric currents have many practical applications, such as in motors and generators, where they are used to produce motion or electricity. They are also used in medical imaging, such as MRI machines, and in electronic devices like speakers and hard drives.

• Introductory Physics Homework Help
Replies
1
Views
202
• Introductory Physics Homework Help
Replies
5
Views
346
• Introductory Physics Homework Help
Replies
12
Views
2K
• Introductory Physics Homework Help
Replies
3
Views
1K
• Introductory Physics Homework Help
Replies
2
Views
234
• Introductory Physics Homework Help
Replies
14
Views
2K
• Introductory Physics Homework Help
Replies
8
Views
643
• Introductory Physics Homework Help
Replies
1
Views
1K
• Introductory Physics Homework Help
Replies
49
Views
3K
• Introductory Physics Homework Help
Replies
6
Views
817