How Do You Calculate Resistance and Current in a Carbon Block Using Ohm's Law?

[LeakyFrog]

Homework Statement

A block of carbon is 3cm long and has a square cross section whose sides are .5cm long. A potential difference of 8.4V maintained across its length.
a)What is the resistance of the block?
b)What is the current in this resistor?

Homework Equations

R=pL/A
where p is resistivity

The Attempt at a Solution

I'm fairly certain i can solve this problem right quick if I could understand what exactly the block looked like. The description just doesn't make sense to me. I'm not sure if you can draw pictures on this or not but a picture would be helpful if someone can make one. Thanks.

 

[ben133]

From what I've read the block is a cuboid. Imagine a square that's 0.5cm by 0.5cm, now stretch that back in the third dimension by 3cm, and Bob's your uncle. A similar shape to a packet of gum.

 

[LeakyFrog]

thanks dude (or dudette)! helped a bunch!

 

[ben133]

No worries mate.

 

[rdl]

I can provide some clarification on the block of carbon described in the problem. The block is a rectangular prism with dimensions of 3cm x 0.5cm x 0.5cm. This means that it has a length (L) of 3cm and a cross-sectional area (A) of 0.5cm x 0.5cm = 0.25cm^2.

Now, let's apply Ohm's Law to solve for the resistance (R) of the block. Ohm's Law states that the resistance of a material is equal to the product of its resistivity (p), length (L), and cross-sectional area (A). In this case, the potential difference (V) is also given as 8.4V. So, we can write the following equation:

R = p x L/A = (8.4V) x (3cm) / (0.25cm^2) = 100.8 ohms

This means that the resistance of the block of carbon is 100.8 ohms.

To solve for the current (I) in this resistor, we can use Ohm's Law again. The relationship between current, voltage, and resistance is given by the formula I = V/R. So, we can plug in the values we know:

I = (8.4V) / (100.8 ohms) = 0.0833 amps

Therefore, the current in this resistor is 0.0833 amps.

I hope this helps to clarify the problem and provide a solution to the questions asked. It is important to note that resistivity is a property of a material, and it is dependent on factors such as temperature and composition. Ohm's Law is a fundamental principle in understanding the behavior of electrical circuits and can be applied in various situations. It is important for scientists to have a solid understanding of these concepts in order to accurately analyze and solve problems in their field of study.