# Calculate the intensity of the Earth's magnetic field

• PRASHANT KUMAR
In summary, a circular coil with 10 turns and a radius of 120 mm is placed parallel to the Earth's magnetic field. When a current of 0.45 A flows through the coil, a compass needle at the center is deflected by 45 degrees. By calculating the magnetic moment and torque, it can be determined that the magnetic field produced by the coil is equal to the Earth's magnetic field, but perpendicular, causing the needle to deflect.
PRASHANT KUMAR

## Homework Statement

a circular coil of radius 120 mm with 10 turns is placed with its plane parallel to the Earth magnetic field . when a current of 0.45 A flows through the coil , a compass needle placed at the centre of the coil is seen to be deflected by an angle of 45 degree to the plane of the coil . the intensity of the Earth magnetic field is calculated to be?

first i calculated the magnetic moment = 10*pi*(0.12)^2*0.45 unit
then i can calculate the torque = cross product of magnetic moment with magnetic intensity of Earth magnetic field = 0.2035 B unit (where B represents the intensity of Earth magnetic field )
how can i take into account the deflection of the needle by 45 degrees and where will torque act ?

Calculating the magnetic moment of the coil doesn't buy you much. How do you think you are going to use it? It's the needle that turns, not the coil. Instead, consider this: The needle aligns itself with the magnetic field it finds itself in. So initially it points along the Earth's field. When the current is turned on, the needle is at 45o from its initial direction. What does this say to you about the total field at the needle and the field produced by the coil?

Sounds like the magnetic field produced from the coil where the compass is placed, is equal to Earth's magnetic field, just perpendicular. This would explain why it would move 45 degrees from its initial position.

## 1. How is the intensity of the Earth's magnetic field calculated?

The intensity of the Earth's magnetic field is calculated by measuring the strength of the magnetic field at various locations on the Earth's surface. This is done using instruments such as magnetometers, which can detect changes in the Earth's magnetic field. The data collected from these measurements is then used to calculate the overall intensity of the Earth's magnetic field.

## 2. What is the unit of measurement used to express the intensity of the Earth's magnetic field?

The unit of measurement used to express the intensity of the Earth's magnetic field is called the Tesla (T). This unit is named after the famous inventor and scientist, Nikola Tesla. The Earth's magnetic field has an average intensity of approximately 31 microteslas (µT) at the Earth's surface.

## 3. How does the intensity of the Earth's magnetic field vary across different locations on the Earth's surface?

The intensity of the Earth's magnetic field varies across different locations on the Earth's surface due to the Earth's magnetic field being non-uniform. This means that the strength of the magnetic field is not the same at all points on the Earth's surface. The magnetic field is stronger near the Earth's poles and weaker near the equator.

## 4. What factors can affect the intensity of the Earth's magnetic field?

Several factors can affect the intensity of the Earth's magnetic field, including the Earth's rotation, the movement of molten iron in the Earth's outer core, and the influence of the Sun's magnetic field. These factors can cause fluctuations in the intensity of the Earth's magnetic field over time.

## 5. Why is it important to calculate the intensity of the Earth's magnetic field?

It is important to calculate the intensity of the Earth's magnetic field because it helps us understand the Earth's structure and how it has evolved over time. The Earth's magnetic field also plays a crucial role in protecting the Earth from harmful solar radiation. Additionally, the intensity of the Earth's magnetic field can impact various technologies, such as navigation systems and satellite communications.

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