Lesson 2 -­‐ ISA Prepara0on Plymstock School
P.J.McCormack
Resistance Prac0cal 29 November 2013 Inves0gate a factor that may affect the resistance of a filament bulb P.J.McCormack
Learning Outcomes. 29 November 2013 By the end of the lesson I will be able to.... Low All.. •  State the meaning of the term resistance •  State the equa;on for Ohms Law Most… •  Calculate the resistance of a filament bulb Some... •  Explain how the current and voltage affects the resistance of a filament bulb High Key Words: resistance, current, voltage, electrons P.J.McCormack
Basic ideas.
Electric current is when electrons start to flow around a circuit.
We use an _________ to measure it and it is measured in ____.
Potential difference (also called _______) is how
big the push on the electrons is. We use a
________ to measure it and it is measured in
______, a unit named after Volta.
Resistance is anything that resists an electric current. It is
measured in _____.”
29/11/2013
(Words:
volts, amps, ohms, voltage, ammeter, voltmeter)
Resistance Resistance is anything that will RESIST
a current. It is measured in Ohms, a
unit named after me.
The resistance of a component can be
calculated using Ohm’s Law:
Resistance
(in Ω)
=
Georg Simon Ohm
1789-1854
V Voltage (in V)
Current (in A)
I R An example ques0on: Ammeter reads 2A A V Voltmeter reads 10V November 29, 2013 1)  What is the resistance across this
bulb?
2)  Assuming all the bulbs are the same
what is the total resistance in this
circuit?
P.J.McCormack 29 November 2013 Current Voltage & Resistance hSp://www.youtube.com/watch?v=Lp7192oVbzI P.J.McCormack
Current, Voltage and Resistance. Equipment •
•
•
•
•
•
29 November 2013 12 volt filament bulb Bulb holder Connec;ng wires Variable power supply Ammeter Voltmeter P.J.McCormack
The Method 29 November 2013 hSp://www.youtube.com/watch?v=BcmYedpm4Do P.J.McCormack
Method 29 November 2013 •  Connect the circuit as shown below •  Switch on the variable power supply to 2V •  Record the readings on the ammeter and voltmeter to two decimal places the turn off the variable power supply •  Calculate the resistance of the bulb by using the equa;on R = V/I •  Repeat the above steps using 4V, 6V, 8V and 10V on the variable power supply P.J.McCormack
29 November 2013 P.J.McCormack
Starter (BoB Ex.) Current November 29, 2013 1.  What is current? 2.  If the current out of the baSery is 6A what is the current at point B and C? B C 3.  What is voltage? 4.  What is Ohms Law? P.J.McCormack
Key Ques0ons. 29 November 2013 1.
2.
3.
4.
5.
What was the independent variable? What was the dependent variable? What safety precau;on must you make? Name two variables that you must control. How would repea;ng my experiment affect my results? 6.  How would comparing my results with some else improve my results? P.J.McCormack
29 November 2013 Q1. Background Research. Name two sources that you used for your research. This can be a: •  Textbook (men;on the publisher) •  The internet. You need the full web address such as…. www.rsc.org.uk /alchemy/limestone P.J.McCormack
29 November 2013 Q1. Background Research You must explain which one of your sources of informa;on is the most useful. You must comment on both, such as… Source 1 gave me a complete method of what to do. Source 2 gave me informa8on about how solar cells work and what affects how much voltage they make. P.J.McCormack
Q2. Control Variable and Preliminary Test. 29 November 2013 This is where you plan what you would do and how it would help you produce a real plan. In this ques;on men;on the how the results you gather would help you such as….. I would adjust the area by moving the card 1 cm each 8me to see if it made a measurable difference to the voltage, if not I would adjust the lamp closer to the solar cell so more light hit the cell or move the card 2 cm at a 8me. P.J.McCormack
Q3. The Plan. 29 November 2013 •  Equipment with volumes, sizes and amounts •  Men;on two variables that must be kept the same in order to make the inves;ga;on a fair test. •  Men;on the independent variable and how this will be varied and the dependent variable. •  Risk assessment, what are the risks and how can they be controlled. •  You may bullet point your method as long as it is well structured in a logical sequence. Check your spelling, punctua0on and grammar and use technical/scien0fic terms P.J.McCormack
Q4. Comparing Results. 29 November 2013 Explain the advantage of sharing results with others? Reproducibility – measurement repeated by another person, or by using different equipment or techniques and the same results are obtained. If all the class results are shared then we can calculate a mean and that would give us a more accurate result. If the results are reproducible I must have carried out the test correctly. P.J.McCormack
Q5. Results Table Independent Variable (unit) 29 November 2013 Dependent variable (unit) P.J.McCormack
Sketch Graph 29 November 2013 •  A line graph that shows the general paSern and the rela;onship between the two variables. •  Sketch graphs do not need to have a scale or points ploSed but they must have labelled axis. P.J.McCormack
Sketch Graph 29 November 2013 P.J.McCormack
Example ISA’s with Examiners Comments 29 November 2013 hSp://store.aqa.org.uk/sciencelab/AQA-­‐CHEM1-­‐EXEMPLAR-­‐CA-­‐AV.PDF hSp://store.aqa.org.uk/sciencelab/AQA-­‐BIOL1-­‐EXEMPLAR-­‐CA-­‐AV.PDF hSp://store.aqa.org.uk/sciencelab/AQA-­‐PHYS1-­‐EXEMPLAR-­‐CA-­‐AV.PDF hSp://store.aqa.org.uk/sciencelab/AQA-­‐CHEM1-­‐EXEMPLAR-­‐CA-­‐HI.PDF hSp://store.aqa.org.uk/support/pdf/AQA-­‐SCIENCE-­‐CONTROLLED-­‐
ASSESSMENT-­‐LEAFLET.PDF hSp://store.aqa.org.uk/sciencelab/AQA-­‐PHYS1-­‐EXEMPLAR-­‐CA-­‐HI.PDF P.J.McCormack
29 November 2013 Measles (000's) Mumps (000's) Rubella (000's) P.J.McCormack
Marking Criteria 29 November 2013 What key point are we going to include? P.J.McCormack