Plymstock School P.J.McCormack Lesson 2 ISA Prepara0on
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Plymstock School P.J.McCormack
Lesson 2 -‐ ISA Prepara0on
Resistance Prac0cal
Inves0gate a factor that may affect the resistance of a filament bulb
29 November 2013
P.J.McCormack
Learning Outcomes. By the end of the lesson I will be able to....
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
29 November 2013
P.J.McCormack
Low
High Key Words: resistance, current, voltage, electrons
29/11/2013
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 _____.”
(Words: volts, amps, ohms, voltage, ammeter, voltmeter)
Georg Simon Ohm 1789-1854
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 = Voltage (in V)
(in Ω) Current (in A)
V
I R
November 29, 2013 P.J.McCormack
V
A
An example ques0on:
1) What is the resistance across this bulb?
2) Assuming all the bulbs are the same what is the total resistance in this circuit?
Voltmeter reads 10V
Ammeter reads 2A
Current Voltage & Resistance hSp://www.youtube.com/watch?v=Lp7192oVbzI
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P.J.McCormack
Current, Voltage and Resistance.
Equipment • 12 volt filament bulb • Bulb holder • Connec;ng wires • Variable power supply • Ammeter • Voltmeter
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P.J.McCormack
The Method hSp://www.youtube.com/watch?v=BcmYedpm4Do
29 November 2013
P.J.McCormack
Method • 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
29 November 2013
P.J.McCormack
29 November 2013
P.J.McCormack
November 29, 2013
P.J.McCormack
Starter (BoB Ex.) Current
1. What is current? 2. If the current out of the baSery is 6A
what is the current at point B and C?
3. What is voltage? 4. What is Ohms Law?
B
C
Key Ques0ons. 1. What was the independent variable? 2. What was the dependent variable? 3. What safety precau;on must you make? 4. Name two variables that you must control. 5. How would repea;ng my experiment affect
my results? 6. How would comparing my results with some
else improve my results?
29 November 2013
P.J.McCormack
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
29 November 2013
P.J.McCormack
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.
29 November 2013
P.J.McCormack
Q2. Control Variable and Preliminary Test.
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.
29 November 2013
P.J.McCormack
Q3. The Plan. • 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
29 November 2013
P.J.McCormack
Q4. Comparing Results. 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.
29 November 2013
P.J.McCormack
Q5. Results Table Independent
Variable (unit) Dependent variable
(unit)
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P.J.McCormack
Sketch Graph • 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.
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P.J.McCormack
Sketch Graph 29 November 2013
P.J.McCormack
Example ISA’s with Examiners Comments
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
29 November 2013
P.J.McCormack
29 November 2013
P.J.McCormack
Measles (000's)
Mumps (000's)
Rubella (000's)
Marking Criteria 29 November 2013
P.J.McCormack
What key point are we going to include?
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