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EMPA Information. Provisional Dates:- Weds 5 th May – Practical (Section A) – All Day (no time limit) consists of two tasks. Fri 7 th May – Written Paper (Section B) 1hr 1/4. Remember Unit 1 exam is on Thursday 27 th May. EMPA Practice. Next week in Friday P1 with Dr. Poulton.
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EMPA Information Provisional Dates:- Weds 5th May – Practical (Section A) – All Day (no time limit) consists of two tasks. Fri 7th May – Written Paper (Section B) 1hr 1/4. Remember Unit 1 exam is on Thursday 27th May.
EMPA Practice Next week in Friday P1 with Dr. Poulton. Following week on Thursday P1 (BK) +P2 (CJP). More will follow...Don’t Panic! I can do more in Phys. Workshop (need advance warning.)
Resistor Rules Electricity Lesson 8
Learning Objectives To know and derive the rules for resistors in series and parallel.
Recap What are the circuit rules for current and potential difference?
Resistors in Series The pd across all the components is equal to the sum of the pds across each component:- Using R=V/I, we can write:-
Resistors in Series The resistance across all three resistors is:- Then cancelling the Is on the right hand side:-
Quick Question (a) What is total resistance of the three resistors connected in series?
Resistors in Parallel The current splits at a junction but the potential difference is the same across both:- Using R=V/I we can say:-
Resistors in Parallel So it follows that:- Dividing throughout by V gives:-
Resistors in Parallel • What is the resistance across the two resistors if R1 = 10 Ω? • R2 = 5 Ω? • If it is a 1.5 V cell evaluate I, I1 and I2?
Practice Calculation What is the resistance across the 4 ohm and 8 ohm resistors? What is the total resistance? What is the current in each part of the circuit?