# Finding the thickness of graphite in a circuit

• janegoldberg
In summary, the conversation is about a homework problem involving drawing a circuit with a pencil and LED. The brightness of the LED and the resistance of the circuit were determined, and the distance and width of the pencil line were given. The conductivity of graphite was also mentioned, and the task is to estimate the thickness of the pencil line in micrometers. However, the person needs to post the problem in the appropriate forum and show their initial attempt at solving it in order to receive help.
janegoldberg

In class, I "drew a circuit" with a pencil. When the LED was moderately bright about 9mA was flowing and so (since I was using a 9V battery), the resistance was about 1 kΩΩ.
At this point, the distance 𝐿L between the battery and the LED was about 10 cm and the width of the pencil line was about 1cm. If the conductivity of the graphite was about 𝜎𝐶≈1000σC≈1000S/m , estimate the thickness (i.e. height above the paper) of the line I drew.

Hi. This is clearly a homework problem and it should be posted in the appropriate forum, which you will find at the very top of the list of forums (have a look). There is a pro forma to fill in which requires you to show what work and reading you have already done. Tell us about the "everything" you have tried.
PF doesn't work as a dial a homework answer service but you can get a lot of help if you go about it in the right way.

berkeman
Thread moved to the schoolwork forums.

@janegoldberg -- please show your initial try at solving this problem so that we can see where you might need help. Per the PF rules, we can only offer tutorial help after you show your work on the problem. It would also help if you attach a sketch of the "graphite wire" that you are saying is used to attach the LED to the 9V battery. Include the dimensions (the ones you know and the unknown you are supposed to solve for). Thanks.

## 1. How do you determine the thickness of graphite in a circuit?

The thickness of graphite in a circuit can be determined by using a specialized tool called a thickness tester. This tool uses a non-destructive method called eddy current testing to measure the thickness of the graphite layer on a circuit board.

## 2. Why is it important to know the thickness of graphite in a circuit?

The thickness of graphite in a circuit is important because it affects the electrical conductivity and performance of the circuit. If the graphite layer is too thin, it may not provide enough conductivity, while if it is too thick, it may cause short circuits or other issues. Knowing the exact thickness can help ensure the circuit functions properly.

## 3. What factors can affect the thickness of graphite in a circuit?

The thickness of graphite in a circuit can be affected by various factors such as the type and quality of the graphite material, the application method, and the environmental conditions during the manufacturing process. It can also be affected by wear and tear over time.

## 4. Can the thickness of graphite in a circuit be measured without specialized equipment?

No, the thickness of graphite in a circuit cannot be accurately measured without specialized equipment. Visual inspection or manual measurements are not precise enough to determine the thickness, and they may also damage the circuit. It is important to use a thickness tester for accurate results.

## 5. Is the thickness of graphite in a circuit the same as the thickness of the entire circuit board?

No, the thickness of graphite in a circuit is not the same as the thickness of the entire circuit board. The graphite layer is just one component of the circuit and is usually much thinner than the overall thickness of the board. It is important to measure the thickness of graphite separately from the thickness of the circuit board.

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