Graphs - IGCSE Edexcel Physics
- 1. IGCSE Edexcel Physics Graphs Practical Questions
- 2. IGCSE Edexcel Physics Getting Started Students are required to know: • To calculate gradient of the graph • To sketch “line of best fit” and “curve of best fit” • Types of graphs: line and bar chart and when and where to use them. • Shapes of graph
- 3. IGCSE Edexcel Physics Calculating gradient • Gradient of straight line can be calculated by the following equation 𝑚 = (𝑦2−𝑦1) (𝑥2−𝑥1) • Example: From the right hand graph 𝑚 = (𝑦2−𝑦1) (𝑥2−𝑥1) 𝑚 = 8 − 6 10 − 6 = 𝟎. 𝟓
- 4. IGCSE Edexcel Physics Independent variable vs Dependent variable • The independent variable is always on the horizontal x-axis, and the dependent variable is always on the vertical y-axis as shown on the right.
- 5. IGCSE Edexcel Physics Types of graph There are many kinds of graph. Graphs with axis (x and y) are basically two types: • Line graph • Bar chart • Lines charts are used for continuous variables and Bar chart are used of discontinuous variables.
- 6. IGCSE Edexcel Physics Line of best fit • Line of best fit is the line that is the most closest to all the points. • It also helps discard anomalous readings
- 7. IGCSE Edexcel Physics Curve of best fit • The curve of best fit needs to be smooth and close to most of its readings • It doesn’t necessarily have to join all the points in the graph
- 8. IGCSE Edexcel Physics Describing Shapes of Graph • Linear relationship: If a graph produce a straight line, then the relationship between the two variables is linear. • Non-linear relationship: If the graph is curved, then the relationship is non-linear.
- 9. IGCSE Edexcel Physics Describing Shapes of Graph • Graphs often pass through origin • Positive/negative correlation: If the gradient of the graph is positive, then it has positive correlation. If the gradient is negative, then the graph has negative correlation • Inverse relationship: The relationship is said to be inverse if the correlation is negative. That is, if one variable’s value increase, the other’s decrease.
- 10. IGCSE Edexcel Physics Tips Graphs are often marked for the following features: • Size: your graph should cover more than 50% of the graph paper • Axis: Label quantity and unit, keep numbers evenly spaced