# Help with designing an investigation

• Jimmy87
In summary, the conversation discusses designing an investigation into transformers using a list of equipment. The main focus is on using all the equipment, including coils of wire, iron core, ammeter, voltmeter, loudspeaker, signal generator and an oscilloscope. The group considers investigating how changing the number of turns on the primary affects the secondary emf, and also discusses the purpose of using a signal generator and an oscilloscope. They also question the use of a loudspeaker and consider the frequency range to test. Finally, they mention using the oscilloscope to see if the waveform on the secondary is unchanged.
Jimmy87

## Homework Statement

We have been asked to design an investigation into transformers. The equipment list given is: coils of wire, iron core, ammeter, voltmeter, loudspeaker, signal generator and an oscilloscope.

## The Attempt at a Solution

I know that you could investigate how changing the number of turns on the primary affects the secondary emf. However, we were asked to try and use all the equipment. What is the point of using a signal generator? Looking online it seems to say to stick to around 50Hz and nothing I have found seems to suggest changing the frequency of the primary current? Could this be done? What could I use the oscilloscope for?

Thanks for any help offered.

Jimmy87 said:
I know that you could investigate how changing the number of turns on the primary affects the secondary emf.

That's correct but only if there is a primary emf. Check your equipment list again. What could you use to generate the primary emf?

Jimmy87
CWatters said:
That's correct but only if there is a primary emf. Check your equipment list again. What could you use to generate the primary emf?

Thanks. Ok, so the signal generator would provide the emf? Why use a signal generator and not a power pack then?

What would you use the oscillioscope for if you already have a voltmeter to measure the secondary emf? Also have no idea about the loudspeaker?

Jimmy87 said:
Thanks. Ok, so the signal generator would provide the emf? Why use a signal generator and not a power pack then?

You could use an AC power supply if you have one (It would be too dangerous to use the AC mains directly).

Jimmy87 said:
What would you use the oscillioscope for if you already have a voltmeter to measure the secondary emf?

I agree there could be some redundancy. Can your voltmeter measure AC or just DC? Has the oscilloscope got two inputs?

Also have no idea about the loudspeaker?

50Hz is just about in the audible range.

Jimmy87
I suspect the idea of the signal generator and oscilloscope is for you to do a frequency sweep of your coil circuit (with sig. gen.) and show the frequency response on the oscilloscope. You can also use the speaker to provide an audio confirmation that the signal starts to attenuate around the particular frequency that you predicted. (I am assuming that the signal generator operates in the audio range.)

Jimmy87
CWatters said:
You could use an AC power supply if you have one (It would be too dangerous to use the AC mains directly).
I agree there could be some redundancy. Can your voltmeter measure AC or just DC? Has the oscilloscope got two inputs?
50Hz is just about in the audible range.

Thanks. It says in my guidance to use the signal generator to observe the operation of the transformer at different frequencies. So in terms of independent, dependent and control variables could I do the following:

Change the frequency of the primary current (independent variable)
Measure the voltage or oscilloscope reading on the secondary (dependent)
Keep the number of turns the same (control)

Would this work? What would be a suitable frequency range to test? 10-50Hz in steps of 10?

I found out from someone else that the oscilloscope is mainly for us to see that the waveform on the secondary is unchanged whatever that means?

## What is the purpose of designing an investigation?

The purpose of designing an investigation is to systematically gather and analyze information in order to answer a specific scientific question or test a hypothesis. It involves planning and organizing the steps and methods to be used in order to obtain valid and reliable results.

## What are the key components of a well-designed investigation?

The key components of a well-designed investigation include a clearly defined research question or hypothesis, a detailed plan outlining the methods and materials to be used, a control group for comparison, careful data collection and analysis procedures, and appropriate conclusions drawn from the results.

## How do you choose the appropriate research methods for an investigation?

The appropriate research methods for an investigation depend on the research question or hypothesis being tested. It is important to consider factors such as the type of data needed, the resources available, and potential biases or limitations. Consulting with experts and conducting a literature review can also help in selecting the most appropriate methods.

## How do you ensure the validity and reliability of an investigation?

To ensure the validity and reliability of an investigation, it is important to carefully design and control all variables, use appropriate and validated measurement tools, and conduct multiple trials or replications. It is also important to consider potential biases and limitations and address them in the design and analysis of the investigation.

## What are some common challenges in designing an investigation?

Some common challenges in designing an investigation include identifying and controlling all variables, selecting appropriate methods and materials, obtaining ethical approval, and addressing potential biases and limitations. It is important to carefully plan and consider all aspects of the investigation in order to address these challenges and obtain valid and reliable results.

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