Review Read the comments I have written in your book. Complete your next steps in PURPLE PEN. Correct any Spelling and Grammar mistakes in PURPLE PEN.

Engage Why do Xboxes and other computer machinary need cooling fans inside them?

Learning Objectives 1. R-A-G your understanding of today’s specification points 2. Highlight the key words START OF LESSON END OF LESSON 2.12 Explain why, when there is an electric current in a resistor, there is an energy transfer which heats the resistor 2.13 Explain the energy transfer (in 2.12 above) as the result of collisions between electrons and the ions in the lattice 2.14 Distinguish between the advantages and disadvantages of the heating effect of an electric current

Draw a line under last lesson’s work and write today’s title in your book... 04/12/2018 c/w Transferring Energy P2.7

Explore What causes resistance? What happens to a wire when there is lots of resistance?

Electron Flow In Circuits

Explain Explain in your own words… What causes resistance? What happens to a wire/electrons when there is resistance?

Explain What causes the heating in each of these picture? Is it useful or not useful?

Solid atoms of the wire make it hard for the electrons (current) to flow. When electrons collide with the electrons in the solid of the wire, they transfer some of their energy to them as heat. We can use this usefully e.g. toaster, light bulbs It can also be annoying as the energy is wasted. Key Notes

Key Notes Resistor in series When resistors are connected in series the resistance increase. This is because the total resistance of a number of resistors in series is equal to the sum of all the individual resistances. In the circuit above, the following applies I1 = I2 = I3 VT = V1 + V2 + V3 And so, therefore, RT = R1 + R2 + R3 Key Notes

Key Notes Resistance in parallel circuits When resistors are connected in parallel the net resistance decreases this is because when resistors are connected in parallel, they have the same potential difference across them. In other words, any components in parallel have the same potential difference across them. For the circuit above, the formula for finding the total resistance of resistors in parallel is 1/RT = 1/R1 + 1/R2 + 1/R3 IT = I1 + I2 + I3 V1 = V2 = V3 And so 1/RT = 1/R1 + 1/R2 + 1/R3 Key Notes

POWER = CURRENT x POTENTIAL DIFFERENCE Extend POWER is the amount of energy transferred each second POWER = CURRENT x POTENTIAL DIFFERENCE WHY does current x voltage give us power? What do these things mean?

POWER = CURRENT x POTENTIAL DIFFERENCE Extend POWER = CURRENT x POTENTIAL DIFFERENCE But also POWER = ENERGY TIME Combining these two… P = I x V E = I x V t E = I x V x t

Power is the amount of energy transferred per second Extend P = I x V E = I x V x t Power is the amount of energy transferred per second E is just the total energy – given by the power (IxV) multiplied by the number of seconds (time) Write the equation Check units & convert if necessary Put numbers in Rearrange Find answer Write units

Evaluate What are YOUR next steps? R-A-G your understanding of today’s specification points START OF LESSON END OF LESSON 2.15 Use the equation: electrical power (watt, W) = current (ampere, A) x potential difference (volt, V) P = I x V 2.16 energy transferred (joule, J) = current (ampere, A) x potential difference (volt, V) x time (second, s) E = I x V x t What are YOUR next steps?

Independent Study Learn Quiz sets 3,4,5 Revise topic 2 Due: Tues 11th