Physics Help: Electricity & Circuits

In summary, the conversation is about a person asking for help with understanding some review problems for a test, specifically finding the power dissipated by R3 in a series circuit with a 12V battery and 3 resistors, and finding the potential difference between two points in a circuit. The person is reminded to use the equations P=IV and P=I^2R, and to find the total resistance in order to calculate the circuit current.
  • #1
MJ
1
0
I have a test tomorrow and I'm having trouble figuring out some of these review problems. Any help would be much appreciated!

1) Find the power dissipated by R3 in a series circuit with a 12V battery with 3 resistors. R1=45ohms R2=200ohms R3=700ohms

I also have a few questions where it asks you to find the potential difference between two points. For example, before and after a resistor in a circuit. How do i do this?

Thank you very much!
 
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  • #2
Remember that P=IV

You have the total voltage, find the total resistsance. Then find how much voltage is used in R3.
 
  • #3
Also, [itex]P=I^2R[/itex]. don't forget (or at least learn how to use Ohm's law) all of the power equations. Find total resistance. You should be able to find the circuit current then apply the above eq. Good luck on the test.
 

1. What is electricity?

Electricity is a form of energy that results from the presence and movement of charged particles, such as electrons, through a conductor. It is responsible for powering many of the devices and technologies we use in our daily lives.

2. What is the difference between AC and DC electricity?

AC (alternating current) electricity is when the direction of the flow of electrons periodically reverses, while DC (direct current) electricity is when the electrons flow in only one direction. AC is typically used for household electricity, while DC is used for batteries and electronics.

3. What is a circuit?

A circuit is a complete path through which electricity can flow. It consists of a source of electricity (such as a battery), conductors (such as wires), and loads (such as light bulbs or motors) that use the electricity.

4. How do resistors affect electricity in a circuit?

Resistors are components that resist the flow of electricity. They can be used to control the amount of current in a circuit, which can affect the brightness of a light bulb or the speed of a motor. They can also be used to divide the voltage in a circuit.

5. What is Ohm's law and how is it used?

Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points, and inversely proportional to the resistance between them. This means that if the voltage increases, the current will also increase, but if the resistance increases, the current will decrease. Ohm's law is used to calculate the relationship between voltage, current, and resistance in a circuit.

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