The electrical grid

12/27/16

“How exactly do we obtain our electricity from power plants?”

 

It is very well known that humanity generates large amounts of electricity using power plants, and then consumes it for their appliances, whether it be residential or industrial. But how does this raw power get transferred? Well, it turns out that this system is in fact the largest machine our civilization has ever built, the electrical grid. The electrical grid is the summation of all of the power transmissions systems which take in energy from a generation source and transport it to our appliances. The electrical grid primarily uses high voltage transmission lines and step-up transformers to accomplish this task.

Ohm-meter

11/27/16

“How can we measure the resistance in an electronic component?”

 

Electronic structures such as resistors play a vital part in the workings of electrical devices through the use of resistance. However, how can we measure such a phenomena empirically? Well, let’s use our engineering mindset to figure it out. Firstly, we should be aware that it is possible to experimentally measure both the voltage and current between two points, and that the resistors of a circuit is equal to the voltage divided by the resistance (R = V/I). Therefore, it would be most rational to combine these two facts, and synthesize a most useful device known as the ohm-meter.

Why do rechargeable batteries wear out?

11/23/16

“So why do they?”

Rechargeable batteries can be a very worthwhile investment. For just a small amount of money, one can save not only save the environment but also much pain irritation from having to unceasingly find new batteries . However, something one very vexatious impinging factor on their worthwhileness is the fact that rechargeable batteries tend to wear out. Specifically, the more one recharges a battery, the less charge the battery will be able to hold. But why does this happen? Well, it all comes down to a the way that it works. Rechargeable batteries charge by using a transfer of ions through an anode and a cathode to convert active energy into potential energy  . However, this process will wear down the anodes and cathodes over time, leading to a degradation of internal materials which in turn leads to increased inefficiency. Therefore, the more time one charges a battery, the less productive it will be.

Resistor coloring

08/20/16

“Why do resistors have different colors?”

 

When looking at resistors, you might notice that they seem to have different colors. Four in fact, all in different bands. What do they mean and what do they imply? Well believe it or not, this different resistor coloring corresponds to different resistance values. This means that users such as yourself can easily find the resistor they require just by looking at the band colors.

The first band (called band A) represents the first figure, the second one t(band b) represents the second figure (some more precise resistors may have an extra band to indicated a further figure), the third band the Decimal multiplier (meaning how much this figure  constructed by the earlier bands will be multiplied by), and the final band represents the tolerance percentage (no band means a 20% tolerance level). A chart of the colors and the corresponding values can be found in the picture above

To get a better idea about how this works, let’s do an example. Let’s say that you find a band with the first band colored gray, the second band colored blue, the third green, and the final one red. This resistor will have a value of 86*10^5 ohms, and a tolerance of +-2%. Now go out there, find yourself some resistors, and try to apply these rules to try to estimated the values!

Series and Parallel

08/18/16

“How can different elements in a circuit be hooked up and what are the effects on current?”

 

When studying electronics, one might wonder, “What are the different ways that we hook up different resistors in a circuit, and how do they affect the circuit current itself?”. Well, let’s think about it.

One way we could hook up everything is to directly connect each element in series. This way, the voltage from the power source will pass through each individual part, giving an associated drop at each one. Due to the fact that they are all directly connected, each resistive element will have the same current pass through it. This makes calculating the final current easily, because we can solve symbolically as follows. Let’s say we have a circuit with 3 resistors, all of different values R1, R2, and R3. Each one of them will have the same current I. Because the voltage drop through all of them combined must be equal to the total voltage V, we can construct the algebraic equation I*R1+ I*R2 + I*R3=V. Due to a common factor of I, we can simplify this equation to be I*(R1+R2+R3)=V. We can then divide the voltage by the total resistance to find the current I = V/(R1+R2+R3). This pattern holds for any number of elements in series. Let’s do a numerical example to cement our knowledge. Let’s take R1=1 ohm, R2= 2 ohm, R3 = 3 ohm, and V = 12 volts. If we do our math right, then we should end up with I=12/(1+2+3) → I=12/6 → I = 2 amps.

Another example that we could do is to to elements, hook them up directly to the voltage source, but do not directly connect them, only have them in parallel. Let’s work out the framework for these paradigm. Since each element is directly hooked up the voltage source, not only must it provide a current to go through each element, but the voltage drop must be the same as the voltage source. So how can we find out the current? Well, it’s actually surprisingly simple. First we must notice that each of the elements obtain an individual current, corresponding to the voltage divided by the resistance, or v/r. We must then notice that the total current I will be all of the individual currents added up, I = V/R1+V/R2+V/R3+….Then, since there is a common factor on each of these elements V (as I = V/R), we can divide everything by the Voltage V, to obtain I/V=1/R1+1/R2+1/R3+… , and if we simply notice that I/V is equal to the inverse of the total resistance Req, we can then represent this equation as 1/Req=1/R1+1/R2+1/R3.. We can obtain an equivalent resistance for all of the elements in parallel, and find the total current by setting it equal to the total voltage or I=V/Req, and find our answer! As one can observe, and a parallel setup, the more elements one adds, the higher the current will be, because all of those elements will need to be supplied with the same voltage drop