1 / 28

If the top light bulb goes out what happens to the other light bulb

If the top light bulb goes out what happens to the other light bulb. The other goes out The other explodes The other stays on The other blinks. [Default] [MC Any] [MC All]. Circuits!. What’s a Circuit?.

jensen
Download Presentation

If the top light bulb goes out what happens to the other light bulb

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. If the top light bulb goes out what happens to the other light bulb • The other goes out • The other explodes • The other stays on • The other blinks [Default] [MC Any] [MC All]

  2. Circuits!

  3. What’s a Circuit? • A circuit is a closed path where charges flow from low to high potential. They can be manipulated on the way.

  4. The Power Source • Provides the difference in potential. It is measured in volts (remember this) • A Cell (battery) is the easiest to see. It converts chemical energy to electrical energy. • This is also called “Electromotive force” (or emf) • Think of “Voltage” as how “wide” the charges are moving.

  5. What is Electric Current? • An electric current is the flow of charge through wires and components. • The greater the current, the more charges are moving! • In which direction does the current flow? • It flows from the negative terminal to the positive terminal. • Measured in Amperes (we say Amps) - +

  6. Circuit Diagram We draw electric circuits using specific symbols (because quite frankly most people can’t draw)…. cell lamp switch wires

  7. Types of Circuits There are two basic types of electrical circuits; SERIES CIRCUITS PARALLEL CIRCUITS

  8. SERIES CIRCUITS The components are connected end-to-end, one after the other. They make a simple loop for the current to flow round. If one bulb ‘blows’ it breaks the whole circuit and all the bulbs go out. (One charge gets stuck, they all get stuck).

  9. PARALLEL CIRCUITS The components are connected side by side. The current has a choice of routes. If one bulb ‘blows’ there is still be a complete circuit to the other bulb so it stays alight.

  10. Resistance • When an object (like a light bulb) resists or diminishes the flow of current, it has resistance. • Resistance is measuredin OhmsSymbol for Ohms: Ω

  11. “Short Circuit” • Just remember that electricity is lazy, and will always take the path of least resistance. • If something (usually a wire) provides a path around a resistor, the electrons will take it!

  12. COMPLEX CIRCUITS Is made up of both series and parallel circuits combined. This is what most circuits in the “real world” are like.

  13. If light bulb R3 goes out, what happens to the rest of the circuit? • R1 and R2 get brighter • R1 stay one, but R2 goes out • R2 goes out and R1 stays on • R1 and R2 go out [Default] [MC Any] [MC All]

  14. Ohm’s Law • Relates the voltage (Volts), current (Amps), and resistance (Ohms) in a circuit. • V = Voltage (in Volts) • I = Current (in Amps) • R = Resistance (in Ω)

  15. A light bulb has a resistance of 30Ω. What voltage would be required to run 4 Amperes of current through the bulb? • 120 V • 7.5 V • .13 V • Voltron [Default] [MC Any] [MC All]

  16. A toaster is connected to a 120-Volt circuit and has 6 Amps of current running through it. What is the resistance of the toaster? • 720 Ω • 20 Ω • .05 Ω • Depends on how brave he is. [Default] [MC Any] [MC All]

  17. If your body resistance is 100,000 Ω, how much current will you experience if you touch the terminals of a 12-Volt battery? • 1,200,000 A • 8,333 A • .00012 A • Depends on how good it taste [Default] [MC Any] [MC All]

  18. Power • Power describes the rate at which electrical energy is transferred. • It is measured in Watts (W). • P = Power (Watts) • I = Current (Amps) • V = Voltage (Volts) OR..

  19. How much power is dissipated in a toaster if it is connected to a 120-Volt circuit and uses 8 Amps? • 960 W • 15 W • .067 W • Zero, it is powered by imagination [Default] [MC Any] [MC All]

  20. A light bulb has a power rating of 60-Watts. How much current would it pull if it has a resistance of 15 Ohms? • 4 A • 2 A • 900 A • 30 A [Default] [MC Any] [MC All]

  21. The End!

  22. Applying Ohm’s Law • It can be used to analyze a whole circuit or a single component. • For the circuit shown • What is the total current? • What is the voltage across a single resistor? • What is the voltage across two resistors?

  23. What if the circuit isn’t so simple? • Can we find the total current through this circuit? • What information do we need? • Voltage is given • Resistance is going to be a little tougher. • We need to find the “equivalent resistance” of the whole circuit.

  24. Equivalent Resistance • Remember that in series, we just add the resistors • R1+ R2+ R3+ … • In parallel, we can use the formula at right. • Do the parallel part 1st and then add it to the series resistor.

  25. Now, back to the original problem: • We have a total resistance of 15Ω and a voltage of 9V

  26. Isn’t electricity supposed to be dangerous? • Well, that depends. • You would think that 1000V would be more dangerous than 100V, right? • It all comes down to Ohm’s law • It is actually the current that kills, not the voltage.

  27. Current kills…Voltage hurts • As current flows through muscle tissue, the muscle fibers contract. • Anything over 10mA can cause you to grab onto a wire and not be able to let go. • At around 75mA, you are unable to breathe • Between 100 – 200mA, the heart fibrillates • Actually, above 200mA, your chances are better because the heart seizes completely

  28. What determines how much current flows? • That depends on the voltage and resistance • Your skin usually has around 100,000 – 500,000 Ω of resistance when dry. • If you get wet or sweaty, that resistance goes way down. • Whether you get hurt depends on the voltage and your skin’s resistance • This is why we could play with the batteries, but it would be dangerous to use wall outlets

More Related