I'm confused about power and voltage.

In summary, voltage is the force that allows electrons to move through a circuit, and it is created by the voltage source. The current is a measure of how many electrons are flowing through the circuit. Power is the amount of work per second that can be done, and it is calculated by multiplying the voltage and current. The resistance in the circuit affects the amount of power that can be produced.
  • #1
user111_23
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I know power is what causes devices to function in a circuit. What role does the voltage have in a circuit?
 
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  • #2
Voltage is like the Force you give the electrons to move through the circuit (hence the name EMF = electro motive force). Technically this is not true, as we now know that the voltage source (i.e. your battery) creates an electric fileld, which leaves the wire and then at your resistors the electric electric field re enters the circuit. You'll learn about this in an electromagnetism course.

A model that my teacher gave me to understand circuit theory is: consider your wires to be pipes - and inside these pipes you have water and little tiny balls. These tiny balls are your electrons. Your battery source (i.e. your voltage source) is like a pump which increases the pressure that the the water and the little balls experience as they flow through your circuit (pipe) system. Your current is a measure of how many of these little balls whizz through the system - like the flow rate in your pipes. Resistances are like drops in the pressue (you could think that the pipe gets smaller so its harder for the balls to squeaze through).

More mathematically the current is dQ/dt - the rate of change of charge carriers with time.

Your Power is like how much pressure you apply to the number of little balls flowing in your fluid. So you could apply a small amount of pressure to a large amount of balls (corresponding to a low voltage but a high current) and this would have the same power as applying a large amount of pressure to a small number of balls (corresponding to high voltage but low current).

More mathematically the power at a point in the circuit is equall to the current multiplied by the voltage drop or voltage gain:
i.e: P = VI

Cheers,
Thrillhouse
 
  • #3
user111_23 said:
I know power is what causes devices to function in a circuit. What role does the voltage have in a circuit?

Voltage tells you how much work a single electron can do. Electric current tells you how many electrons you use per second. The product (voltage * electric current) tells you how much work per second you can do, which is also called power.

Water pipe analogy:
Voltage = height difference between two points of the pipe
Electric current = amount of water that flows per second
Power = Voltage * Electric current
 
  • #4
And Power is related to the Square of the Voltage.

P=V 2 /R

R is the resistance.
 

1. What is the difference between power and voltage?

Power and voltage are two different aspects of electricity. Voltage is the measure of the force that pushes an electric current through a conductor, while power is the rate at which energy is being transferred or used by an electric circuit. In simpler terms, voltage is the potential difference between two points, while power is the amount of work being done by the electric current.

2. How are power and voltage related?

Power and voltage are mathematically related through Ohm's Law, which states that power (P) is equal to the product of voltage (V) and current (I). This means that an increase in voltage can result in an increase in power, as long as the current remains constant. Similarly, a decrease in voltage can lead to a decrease in power, if the current remains constant.

3. Can power and voltage be measured separately?

Yes, both power and voltage can be measured separately using different instruments. Voltage is measured using a voltmeter, which is connected in parallel to the circuit, while power is measured using a wattmeter, which is connected in series to the circuit. These instruments provide accurate readings of the respective quantity.

4. How does power and voltage affect electrical devices?

The power and voltage requirements of an electrical device are important factors to consider for its proper functioning. If the voltage supplied to a device is too low, it may not have enough energy to operate. On the other hand, if the voltage is too high, it can cause damage to the device. Similarly, if the power supplied to a device is insufficient, it may not work properly, while excess power can cause overheating and potential damage to the device.

5. Can power and voltage be changed or controlled?

Yes, power and voltage can be changed or controlled using various methods. For voltage, a transformer can be used to step-up or step-down the voltage level. For power, a resistor or other electrical components can be used to adjust the amount of power being supplied to a circuit. In addition, power and voltage can also be controlled through the use of switches, fuses, and other protective devices.

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