# Distance relationship between primary/secondary coils

• tima89
In summary, a simple experiment was conducted on AC transformers using an AC supply, a big primary coil, a smaller secondary coil, a smaller metal rod, and a voltmeter. The procedure involved connecting the AC supply to the primary coil, keeping the voltage constant, and placing the secondary coil inside the primary coil. The secondary coil was then raised a certain distance from the primary coil and the voltage was measured at each step. The results showed a sin (or cosine) graph, but the equation governing the pickup voltage as a function of distance and the equation describing the 3-D shape and intensity of the magnetic field created by a wire loop are still unclear.
tima89
We have done a simple experiment on AC transformers.
Given: AC Supply. Big primary coil. Smaller secondary coil. Even smaller metal rod. (They all fit into each other) Voltmeter
What we did:
Connected AC supply to the primary coil. Voltage kept constant at all times
Secondary coil was placed in the primary coil, and connected to a voltmeter.
procedure:
Secondary coil was raised X distance from the primary coil. (Measured top to top).
Voltage on the secondary coil measured with each step.

Now, our results (Voltage vs. Distance) showed parts of a sin (or cosine) graph, and we are having a hard time justifying it. (i know that flux is BAcos(theta)
I would be very pleased if someone could explain it.

What equation should govern the pickup voltage as a function of distance? What equation describes the 3-D shape and intensity of the magnetic field created by a wire loop?

I would first like to commend you on conducting a simple experiment on AC transformers. It is important to understand the principles behind these devices as they are widely used in various applications.

Now, let's discuss the distance relationship between the primary and secondary coils. The results you obtained, showing a part of a sine or cosine graph, can be explained by the principle of electromagnetic induction. This principle states that when a changing magnetic field passes through a conductor, it induces a voltage in that conductor.

In your experiment, the AC supply passing through the primary coil creates a changing magnetic field. As the secondary coil is placed inside the primary coil, it is exposed to this changing magnetic field, which induces a voltage in the secondary coil. This voltage is measured by the voltmeter.

Now, as the secondary coil is moved away from the primary coil, the strength of the changing magnetic field decreases. This results in a decrease in the induced voltage in the secondary coil, which is reflected in your results as a decrease in voltage with increasing distance.

The fact that your results show a part of a sine or cosine graph can be explained by the equation you mentioned, which is the formula for calculating the flux (magnetic field) passing through a conductor at an angle (theta). As the secondary coil is moved away from the primary coil, the angle (theta) between the two coils increases, resulting in a decrease in the flux passing through the secondary coil.

In conclusion, your experiment has successfully demonstrated the principle of electromagnetic induction and the relationship between the distance of the primary and secondary coils and the induced voltage. I hope this explanation helps to clarify your results and the justification behind them.

## 1. What is the purpose of having a distance relationship between primary and secondary coils in a transformer?

The distance relationship between primary and secondary coils in a transformer is essential for efficient energy transfer. It allows for the magnetic field generated by the primary coil to induce a current in the secondary coil, which then powers the load connected to it.

## 2. How does the distance between the primary and secondary coils affect the efficiency of a transformer?

The distance between the primary and secondary coils plays a critical role in the efficiency of a transformer. If the distance is too large, the magnetic field may not be strong enough to induce a current in the secondary coil, resulting in a loss of energy. On the other hand, if the distance is too small, it can cause electrical shorts and decrease efficiency.

## 3. Can the distance between primary and secondary coils be adjusted?

Yes, the distance between primary and secondary coils can be adjusted by physically moving the coils closer or farther apart. This can be done during the manufacturing process or through the use of adjustable spacers or shims. The optimal distance will depend on the specific design and application of the transformer.

## 4. How does the number of windings in the primary and secondary coils affect the distance relationship?

The number of windings in the primary and secondary coils is directly related to the distance relationship. A larger number of windings in the primary coil will result in a stronger magnetic field, which can compensate for a slightly larger distance between the coils. However, if the number of windings in the secondary coil is too high, it can result in excessive voltage and potential damage to the load.

## 5. Is there a specific distance relationship that is ideal for all transformers?

No, there is not a one-size-fits-all distance relationship for all transformers. The optimal distance will vary depending on factors such as the size and design of the transformer, the type of load being powered, and the desired efficiency. It is essential to carefully consider these factors when determining the distance between primary and secondary coils in a transformer.

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