Dependent Variable: The expected outcome of the experiment is to find out how the color of an object affects its ability to hold heat. So, it is evident that the measured temperature of water in each flash is the dependent variable.

Independent Variable: The variation that is brought about in four of the cans is their colours. Hence, the colour of the conical flasks is the independent variable.

Controlled Variable:

• Sunlight: What affects the rise or fall in the temperature of water in the flask is the amount of heat received from the sun. Subodh can control the duration for which the conical flasks are kept in the sunlight. He can also adjust the direction of sunlight falling on the flasks.
• Water: The quantity and purity of water used in the experiment is also a controlled variable.
• Other factors such as the specific heat capacity of a substance, its area, and mass also affect the quantity of heat (to be studied later in Heat, Q = ms 'dt'). The material used to make the flask is a controlled variable. Furthermore, its dimensions are controlled.

The controlled variables must be the same for all of the four conical flasks. Otherwise, Subodh may observe errors in his experiment.

Remember, Subodh must also consider other factors. For instance, the flasks should be kept on insulating surfaces. The thickness of the colour coating must be uniform. The thermometer used to measure the temperature of the water in all four flasks must have the same precision and accuracy.

Learn more about Dependent, Independent, and Controlled Variables.