1 / 24

Do now!

Do now!. Can you continue the questions you started last lesson? Page 221 Question 3 Page 223 Questions 2 & 3 Page 225 Questions 3, 6 & 7. Last lesson. How the motor effect can build a motor Electromagnetic induction. D.C.Motor.

zared
Download Presentation

Do now!

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. Do now! Can you continue the questions you started last lesson? Page 221 Question 3 Page 223 Questions 2 & 3 Page 225 Questions 3, 6 & 7

  2. Last lesson • How the motor effect can build a motor • Electromagnetic induction

  3. D.C.Motor Commutator ensures that every half rotation the current direction reverses in the coil brushes

  4. D.C.Motor

  5. Electromagnetic induction If a magnet is moved inside a coil an electric current is induced (produced) COPY this please!

  6. Electromagnetic induction A electric current is induced because the magnetic field around the coil is changing.

  7. Generator/dynamo A generator works in this way by rotating a coil in a magnetic field (or rotating a magnet in a coil)

  8. Motor = generator If electric energy enters a motor it is changed into kinetic energy, but if kinetic energy is inputted (the motor is turned) electric energy is produced!

  9. Today’s lesson - Transformers

  10. Today’s lesson - Transformers Can you gather around Mr Porter?

  11. Transformers A transformer consists of 3 main parts

  12. Transformers A changing current in the primary coil produces a changing magnetic field in the coil. This changing magnetic field induces a changing current in the secondary coil.

  13. Changing voltages The ratio of the number of turns on the coils equals the ratio of the voltages Vp/Vs = Np/Ns # of turns = Ns # of turns = Np

  14. Changing voltages A transformer where the voltage rises is called a step-up transformer

  15. Changing voltages A transformer where the voltage falls is called a step-down transformer

  16. No energy for nothing However, no new energy is made

  17. No energy for nothing Power in = power out VpIp = VsIs

  18. a.c. only Because transformers rely on induction (changing fields), they only work with alternating current (a.c.)

  19. Why do we need transformers?

  20. Why do we need transformers? Current flowing through wires causes them to get hot and energy is lost.

  21. Why do we need transformers? Keeping the current low means electricity can be transported long distances without losing too much energy.

  22. Why do we need transformers? However, in order to send a large quantity of energy, high voltages are needed.

  23. Transmission of Electricity Step-up Step-down

  24. Let’s try some questions! Page 221 Question 3 Page 223 Questions 2 & 3 Page 225 Questions 3, 6 & 7 Mr Porter wants you to finish these for homework PLUS the questions he is now giving you. Due Tuesday 20th Oct.

More Related