We say that voltage is like pressure, or like gravitational potential energy, because we're trying to draw an analogy to something that you can see or feel (because you can drop a rock on your toe, or feel the pressure in a balloon when you blow it up). What voltage is gets abstract (hence the analogies). The total voltage you get from one out and back, even with a high temperature difference is pretty small.

Understanding the Context

By putting many of these out and back combinations together, you can get a useful voltage. A single out and back is called a thermocouple, and can be used to sense temperature. Many together is a thermocouple generator. Yes, those actually ...

Key Insights

The voltage only needs to be slightly above the forward voltage rating of the LED. A common way to control brightness is through pulse width modulation (PWM). Instead of giving a LED less voltage, to dim it, you give it the full voltage, but in repeating bursts. The duty cycle determines brightness. How do I calculate the voltage drop over wires given a supply voltage and a current?

Final Thoughts

How do I anticipate on voltage drop so that the final load has the correct supply voltage? What will be the power Likewise, if the current and voltage are below a certain level, a person can--given enough time--safely absorb an arbitrarily large amount of electrical energy. Further, if voltage is sufficiently low, the amount of current that can flow as a consequence of such voltage will be too low to cause harm. How would one go about using a 12 V DC power source to power something which needs 4.5 V DC using resistors? Is there a way to determine how much adding a resistor would drop the voltage? 7 One word: Resistance.

Recall that Voltage is calculated by multiplying the current by the resistance. You can have a high potential difference (which is what voltage is), and a low current, simply by having a high resistance in place to block that current. Think of it like a water hose turned on full blast, with a hose gun attached to the end. How is it possible to have high voltage and low current?