1 / 21

Measurements in a Circuit

Measurements in a Circuit. With Ohm’s Law and Watt’s Law. What is Charge?. HOW IS IT DEFINED? Charge : refers to the number of electrons present . HOW IS IT MEASURED? The unit for charge is a Coulomb. Abbreviation = C. One Coulomb is equal to 6.24x10 18 electrons or protons.

ondrea
Download Presentation

Measurements in a Circuit

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Measurements in a Circuit With Ohm’s Law and Watt’s Law

  2. What is Charge? HOW IS IT DEFINED? • Charge: refers to the number of electrons present. HOW IS IT MEASURED? • The unit for charge is a Coulomb. • Abbreviation = C. • One Coulomb is equal to 6.24x1018 electrons or protons. HOW IS IT REPRESENTED? • The symbol for charge is a lower-case q.

  3. Charge on the move… • Charge will only flow if there is a charge pusher. • A battery, charged capacitor, or generator.

  4. What is Current? HOW IS IT DEFINED? • Current: flow of electric charge over time HOW IS IT MEASURED? • The unit for current is an Ampere (Amp). • Abbreviation = A. • For example you may have I=3A in a circuit. HOW IS IT REPRESENTED? • The symbol for current is an I.

  5. From the definition we can say that: I = q t *t =time Example: I = 0.5C 4s I = 0.125 A Current Formula

  6. What level of current is dangerous to people?

  7. Current can kill…. • Current in a circuit poses a danger. • It is essential if you are working on a circuit that you know the value of the current to protect yourself.

  8. What is voltage? HOW IS IT DEFINED? • Voltage: potential of a voltage source to cause charge to flow. HOW IS IT MEASURED? • The unit for voltage is the Volt. • Abbreviation = V. • For example, outlets in your house are approximately 120 Volts. HOW IS IT REPRESENTED? • The symbol for voltage = V.

  9. What is resistance? HOW IS IT DEFINED? • Resistance: a property that determines how much current will flow. • More resistance = less current HOW IS IT MEASURED? • The unit for resistance is the Ohm. • Abbreviation = Ω HOW IS IT REPRESENTED? • The symbol for resistance is an R.

  10. Resistance Increases if… • …LENGTH increases. • …AREA increases. • …TEMPERATURE increases. • Resistance can also vary depending on the type of material used. • Any object can be a resistor, if it slows down the current.

  11. How are V, I and R related? • Ohm’s Law relates V, I and R. • Voltage is equal to the current multiplied by the resistance in a circuit. V= I R

  12. What does this mean? As voltage increases current also increases. As resistance goes up, the current decreases. V = I R What will happen?

  13. The Triangle • Just cover up the quantity you are trying to find to find the formula you need to use. V I R

  14. Ohm’s Law Examples • If you want to find Voltage: V = IR If I= 2 A and R = 5 Ohms Then, V= 2*5 = 10 Volts!

  15. Ohm’s Law Examples • If you want to find Resistance in Ohm’s: R = V ÷ I If V = 9 Volts and I = 4 A Then R = 9 ÷ 4 = 2.25 Ohms!

  16. Ohm’s Law Examples • If you want to find Current in Amps: I = V ÷ R If V= 1400 V and R = 2 Ohms Then, I = 1400 ÷ 2 = 700 Amps! • Think about it: What effect would this have on the human body?

  17. Power HOW IS IT DEFINED? • Power: a measurement of the rate at which energy is transferred. HOW IS IT MEASURED? • The unit for power is the Watt. • Abbreviation = W HOW IS IT REPRESENTED? • The symbol for power is a P.

  18. P = IV Power is equal to the current multiplied by the voltage in a circuit. Power Formula

  19. The Triangle • Just like you use the Ohm’s law triangle, you can use the Watt’s Law triangle. Just cover up the quantity you are trying to find. P I V

  20. What if you don’t know the voltage? P = I2 R

  21. What if you don’t know the current? P = V2 R

More Related