2. Current

3. Current There are two kinds of current: There are two kinds of current:

4. Current 1.Direct current

5. Current There are two kinds of current: There are two kinds of current: 1.Direct current 2.Alternating current

6. Direct current

7. DC flows in one direction DC flows in one direction DC is the kind of current that comes from batteries. DC is the kind of current that comes from batteries.

8. Alternating current

9. AC flows back and forth rapidly. In North America it flow back and forth 60 times a second. This is called 60 Hertz

11. Why do we use AC instead of DC?

16. Why we use AC instead of DC AC can be more easily transmitted over long distances than DC. AC can be more easily transmitted over long distances than DC.

17. Why we use AC instead of DC AC can be more easily transmitted over long distances than DC. AC can be more easily transmitted over long distances than DC. Why? Why?

18. Why we use AC instead of DC AC can be more easily transmitted over long distances than DC. AC can be more easily transmitted over long distances than DC. Why? Why? Because of transformers Because of transformers

20. Transformers

21. Step-up transformers Turns lower voltages into higher ones Turns lower voltages into higher ones Fewer turns on the primary side than the secondary one. Fewer turns on the primary side than the secondary one.

22. Step-up transformers

23. Step-down transformers Turns higher voltages into lower ones. Turns higher voltages into lower ones. More turns on the primary side than the secondary one. More turns on the primary side than the secondary one.

24. Step-down transformers

26. Electromagnetic Induction

27. E.i. describes the production of electricity by using a magnetic field. E.i. describes the production of electricity by using a magnetic field. This is how generators “make” electricity. This is how generators “make” electricity. Generators convert mechanical energy into electrical energy. Generators convert mechanical energy into electrical energy.

28. Electromagnetic Induction

30. POWER

31. POWER Power is the rate at which devices use energy. Power is the rate at which devices use energy.

32. POWER The unit of power measurement is the watt (W). It measures how many units of energy are used per second. The unit of power measurement is the watt (W). It measures how many units of energy are used per second.

33. POWER Power is the rate at which devices use energy. Power is the rate at which devices use energy. The unit of power measurement is the watt (W). It measures how many units of energy are used per second. The unit of power measurement is the watt (W). It measures how many units of energy are used per second. Energy is measured in joules (J) Energy is measured in joules (J)

34. POWER The power rating of a device is directly proportional to the current flowing through the device and the voltage in the circuit. The power rating of a device is directly proportional to the current flowing through the device and the voltage in the circuit.

35. POWER In other words... In other words...

36. POWER The power rating of a device is directly proportional to the current flowing through the device and the voltage in the circuit. The power rating of a device is directly proportional to the current flowing through the device and the voltage in the circuit. In other words... In other words... The Power Formula Power = current x voltage Power = current x voltage P = I x V P = I x V

37. Math Time!!

38. Now, stop writing (and complaining) and watch this.this