Types of Variables

1. What is meant by the term independent variable?
2. What is meant by the term dependent variable?
3. What is meant by the term control variable?
4. In the spring extension required practical, what is the independent variable?
5. In the spring extension required practical, what is the dependent variable?
6. Give two control variables in the spring extension required practical.
7. Explain why control variables must be kept the same throughout an investigation.
8. A student investigates how the voltage across a lamp affects the current through it. Identify the independent variable and the dependent variable.
9. A student investigates how the height of a ramp affects the speed of a toy car. Give one independent variable, one dependent variable and one control variable.
10. A student investigates how the temperature of water affects the time taken for a sugar cube to dissolve. Identify the independent variable, dependent variable and two control variables.

Answers to Types of Variables

1. The independent variable is the variable that is changed by the investigator.
2. The dependent variable is the variable that is measured during the investigation.
3. A control variable is a variable that is kept the same throughout the investigation.
4. The independent variable is the force (or weight) applied to the spring.
5. The dependent variable is the extension of the spring.
6. Any two from: use the same spring, keep the ruler vertical, keep the pointer horizontal.
7. Control variables must be kept the same so that any changes in the dependent variable are caused only by changes in the independent variable.
8. Independent variable: voltage across the lamp. Dependent variable: current through the lamp.
9. Independent variable: height of the ramp. Dependent variable: speed of the toy car. Control variable: same toy car.
10. Independent variable: temperature of the water. Dependent variable: time taken for the sugar cube to dissolve. Control variables: size of the sugar cube and volume of water.