1. Garfield graphics reproduced with kind permission from PAWS Inc. – All rights reserved – LOJ October 2007 Variables (Electricity)

2. Garfield graphics reproduced with kind permission from PAWS Inc. – All rights reserved – LOJ October 2007 Q1. Jack performed an experiment to find out the relationship between the current that flowed through a lamp and the p.d. (voltage) across it. He changed the potential difference across it (the voltage) in equal steps from 0V to 10V (a) What was the dependent variable in his investigation? (b) What was the independent variable in his investigation? (c) What type of variable was the voltage – continuous or discrete?

3. Garfield graphics reproduced with kind permission from PAWS Inc. – All rights reserved – LOJ October 2007 Q1. Jack performed an experiment to find out the relationship between the current that flowed through a lamp and the p.d. (voltage) across it. He changed the potential difference across it (the voltage) in equal steps from 0V to 10V (a) What was the dependent variable in his investigation? (b) What was the independent variable in his investigation? (c) What type of variable was the voltage – continuous or discrete? Current The potential difference – the voltage Continuous You can have any value for the voltage – he just CHOSE whole numbers!

4. Garfield graphics reproduced with kind permission from PAWS Inc. – All rights reserved – LOJ October 2007 Q2. William performed an experiment to find out the relationship between the current that flowed through a lamp and the voltage across it. He changed the current in equal steps of 0.25A from 0A to 2.5A (a) What was the dependent variable in his investigation? (b) What was the independent variable in his investigation? (c) What type of graph should he use to display his results?

5. Garfield graphics reproduced with kind permission from PAWS Inc. – All rights reserved – LOJ October 2007 Q2. William performed an experiment to find out the relationship between the current that flowed through a lamp and the voltage across it. He changed the current in equal steps of 0.25A from 0A to 2.5A (a) What was the dependent variable in his investigation? (b) What was the independent variable in his investigation? (c) What type of graph should he use to display his results? Current Potential difference - voltage A line graph because they are both continuous variables

6. Garfield graphics reproduced with kind permission from PAWS Inc. – All rights reserved – LOJ October 2007 Q3 James decided to investigate which metal was the best conductor. He put a fixed voltage across wires of 10 different materials and measured the current that passed through them. To make it a fair test he made sure the diameter and length of each of the wires was the same. (a) What was the independent variable in his investigation? (b) What was the dependent variable in his investigation? Name the control variables. What type of graph should he use to display his results? What type of variable is the independent variable – categoric or continuous? What type of variable is the dependent variable – categoric or continuous?

7. Garfield graphics reproduced with kind permission from PAWS Inc. – All rights reserved – LOJ October 2007 Q3 James decided to investigate which metal was the best conductor. He put a fixed voltage across wires of 10 different materials and measured the current that passed through them. To make it a fair test he made sure the diameter and length of each of the wires was the same. (a) What was the independent variable in his investigation? (b) What was the dependent variable in his investigation? Name the control variables. What type of graph should he use to display his results? What type of variable is the independent variable – categoric or continuous? What type of variable is the dependent variable – categoric or continuous? The material Current Voltage, length and diameter of conductor Bar chart Categoric Continuous

8. Garfield graphics reproduced with kind permission from PAWS Inc. – All rights reserved – LOJ October 2007 Remember YOU pick the independent variable and change it by a regular amount. The variable that changes because of this is the dependent one!