Understanding Air-Core Coils and Magnetic Flux Lines

[iLuveLfenLied]

1. an air-core coil consists of 10 layers, and each layer is 11cm long and has 400 turns. the average radius of the layers is 2.25 cm. the flux density within the coil can be closely approximated by using the formula: B=µIN/2r
which of the following best describes this statement?
1) true always
2)True only if the current flow is relatively small
3)false always
4)false only if the current flow is relatively small

.....

2. flux lines are
1)discrete lines of concentrated magnetic force
2)used only to describe the direction of a magnetic field
3)used only to indicate the magnitude of a magnetic field
4)a tool devised by scientists to aid in analyzing magnetic force

my answer is 1 and 2?

 

[anathema]

Your answer is correct. The statement is describing a formula used to approximate the flux density within an air-core coil, and it will be true as long as the current flow is relatively small. Flux lines are also discrete lines of concentrated magnetic force and can be used to describe the direction and magnitude of a magnetic field.

 

[baba89]

I would like to provide a response to the content about air-core coils and magnetic flux lines. Firstly, the statement about the formula for approximating the flux density within the coil is correct. This formula, B=µIN/2r, is commonly used to calculate the magnetic field strength within a coil. However, it is important to note that this formula is an approximation and may not be accurate in all situations. It is more accurate for smaller currents, but as the current increases, other factors such as the coil's resistance and self-inductance may need to be considered.

Secondly, the statement about flux lines is partially correct. Flux lines are indeed lines of concentrated magnetic force, but they are not discrete lines. They represent the continuous flow of magnetic flux through a magnetic field. Additionally, flux lines are not only used to describe the direction of a magnetic field, but they also indicate the magnitude of the field. Therefore, the correct answer would be 1) discrete lines of concentrated magnetic force and 3) used to indicate the magnitude of a magnetic field. Flux lines are a useful tool for visualizing and analyzing magnetic fields, but they were not specifically devised by scientists for this purpose. They are a natural phenomenon that has been observed and studied by scientists.