# How to measure the magnetic field/ induced fem in a system

In summary: Yes, the variation of the magnetic flux can be calculated using the following equation:Fv = -N ΔΦ/ΔtWhere Fv is the variation of the magnetic flux, N is the number of turns of the disk, and ΔΦ is the change in magnetic flux.

## Homework Statement

Hello, this is like an experiment of engineering.It is called a induction stove. The system consists of a bycicle, where I am going to pedal. This will turn a disk that have 20 small magnets around its circuference. Once the disk starts to turn, it will produce a constant change in the magnetic flux I think. This will produce an induced electric current that will heat a water in a pot.

I can find the energy exerted by the person to pedal the bycicle and the energy to heat the water, since I could measure by using Q=m.Cp ( Tf-to) / time

I also can find the total efficiency of the system by n= energy produced/ energy delivered , where energy produced is the energy due the heat and the energy delivered is the power exerted by the person to pedal. In my sistem I found a efficiency of 30%. So, the 70% is lost due the friciton in the chains and I think I also have losses in the magnets.

Only for curiosity, I would want to know how I can compute the magnetic field, magnetic flux, varation of the magnetic flux, induced fem and current.

## Homework Equations

The equations I know are:

Φ=B.A.cosθ (But I don't know how to find the magnetic field, and I am not sure if that A is referring to the area of the disk) I don't think so, because in a normal excercise, that area is reffering to the area of the spire that is turning around a magnetic field.

Emf = -N ΔΦ/Δt

## The Attempt at a Solution

What I think I can do is to measure the resistance of the pot with a multimeter I think ( not sure how I can measure the resistance of that). Once I know the resistance , i can find the induced current with P=I.R^2 , where P would be almost the same value that Q (power delivered to the water, that I am able to measure easily)
Once I find the Induced curent, I think I could measure the variation of the magnetic flux somehow ( but no sure how)In my experiment I don't have to measure all those things, it is just for curiosity. I hope someone could say me if it is possible to measure all those variables, or if I need to know some data else.

Once I find the Induced curent, I think I could measure the variation of the magnetic flux somehow ( but no sure how)

There are a range of different instruments that can measure magnetic field strength. The gauss meter is a hand-held device that provides a simple way of performing such measurements.

ARPANSA has two different gauss meter models available for hire, which are a Sypris Model 4080 and an EMDEX Snap. Both instruments operate in a similar manner and they are shown in the image above.

But is there any formula that allow me to compute the variation of the magnetic flux knowing the angular velocity and radius of the disk?

drvrm

## 1. How do I measure the magnetic field in a system?

To measure the magnetic field in a system, you will need a magnetic field sensor such as a magnetometer or a Hall effect sensor. These sensors can be placed inside the system to measure the strength and direction of the magnetic field. Additionally, you will need to calibrate the sensor to ensure accurate measurements.

## 2. What is the unit of measurement for magnetic field?

The unit of measurement for magnetic field is Tesla (T) in the International System of Units (SI). Other commonly used units include Gauss (G) and Oersted (Oe).

## 3. How do I calculate the induced fem in a system?

The induced fem (electromotive force) in a system can be calculated using Faraday's law of induction, which states that the induced fem is equal to the rate of change of magnetic flux through a surface. This can be expressed as E = -dΦ/dt, where E is the induced fem, Φ is the magnetic flux, and t is time.

## 4. What factors can affect the accuracy of magnetic field measurements?

Several factors can affect the accuracy of magnetic field measurements, including the sensitivity and calibration of the sensor, the presence of external magnetic fields, and the distance between the sensor and the source of the magnetic field. It is important to carefully consider and control these factors to obtain accurate measurements.

## 5. Can I measure the magnetic field of any material?

No, not all materials have measurable magnetic fields. Only materials that are ferromagnetic, paramagnetic, or diamagnetic will exhibit measurable magnetic fields. Other materials, such as non-magnetic metals and plastics, will not have measurable magnetic fields. Additionally, the strength of the magnetic field will vary depending on the type of material and its composition.

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