# How Does Magnetism Work in Different Scenarios?

• James2911
In summary, for the first question, you can use the formula B=μ₀/(2πr) to calculate the magnetic field of the coil at a given distance from the center. For the second question, you can use Biot-Savart's Law to calculate the magnetic field due to each of the charges and add them together to get the total magnetic field at point P. And for the third question, you can use the principle of superposition to calculate the total magnetic field due to both current-carrying wires and find the equation of the line on which the magnetic field is zero.
James2911
New poster has been reminded to use the Homework Help Template when posting schoolwork questions, and to post only one question per thread.
Hi. I have three questionns to ask.
1. A very close point on the axis foo a current carrying circular coil (x<<<R) of radius R, the value of magnetic field decreases by a fraction of 5% with respect to the center value. The position of the point from the center of the coil is:
(a) R/10^1/2
(b) R/30^1/2
(C) R/50^1/2
(d) R/150^1/2

2. A charge +2q moves vertically upwards with speed v, a second charge -q moves horizontally to the right with the same speed v, and a third charge +q moves horizontal to the right with the same speed v. The point P is located a perpendicular distance a away from each charge as shown in the figure. The magnetic field at P is ..

Here’s the diagram:

-q ----------> v
|
| ^ v
| |
| |
. P ----------o +2q
|
|
|
o---------> v (+q)

Out of the page with magnitude u(naught) 4qv/4pia^2

1. The equation of line on which magnetic field is zero due to system of two perpendicular infinitely long current carryng straight wire is :-
^ +Y axis
|
| (current flowing thru here is 3I)
|
|
---------------------------------------------------------> x
| (current flowing in +x is I)
|

Since the above 2 diagrams might not be clear, I am uploading screenshots for the same.1. I tried the first question thinking as a Bionomial expression, and getting x = .794R which is not even in the option.

2.I've always solved problems in which only a wire is involved, either square, triangle, straight shapes. But not charges. Do we apply Biot Savart law here? I am able to determine the direction of the magnetic field via knocking rule but have completely no idea about the magnitude.

3. I am guessing, since we want it to be zero, we will place it on X axis first, so that the field due to itself is zero and then at a distance of 3y it will be zero from the y-axis as well or so.

Any help would be appreciated!

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Last edited:
For the first question, you can use the formula B=μ₀/(2πr) to calculate the magnetic field of the coil at a given distance from the center. This will tell you how much the field has decreased by a fraction of 5%. For the second question, you can use Biot-Savart's Law to calculate the magnetic field due to each of the charges. You will need to add the fields together to get the total magnetic field at point P.For the third question, you can use the principle of superposition to calculate the total magnetic field due to both the current-carrying wires. The equation of the line on which the magnetic field is zero will be the sum of the equations of the lines on which the magnetic field from each wire is zero.

## 1. How does magnetism work?

Magnetism is the force that causes objects with magnetic properties to attract or repel each other. It is caused by the alignment of electrons within atoms, which creates a magnetic field. This field is invisible, but its effects can be seen when interacting with objects that have magnetic properties.

## 2. What are the different types of magnets?

There are three main types of magnets: permanent, temporary, and electromagnets. Permanent magnets, such as bar magnets, retain their magnetism without an external power source. Temporary magnets, like paperclips, only exhibit magnetic properties when in the presence of a strong magnetic field. Electromagnets are created by running an electric current through a metal coil, which produces a magnetic field.

## 3. How do magnets attract and repel?

Opposite poles of magnets (North and South) attract each other, while like poles (North and North or South and South) repel each other. This is due to the alignment of the electrons within the atoms of the magnet, which create the magnetic field. The closer the magnets are, the stronger the force of attraction or repulsion will be.

## 4. Can magnets lose their magnetism?

Yes, magnets can lose their magnetism over time. This can happen due to exposure to heat, strong magnetic fields, or physical damage. However, some materials, like iron, can be magnetized again by placing them in a strong magnetic field.

## 5. What are the practical applications of magnetism?

Magnetism has a wide range of practical applications in our daily lives. It is used in compasses for navigation, motors and generators for electricity, speakers and headphones for sound, and in credit cards and hard drives for data storage. It also plays a crucial role in medical imaging technology, such as MRI machines.

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