a. The IGCSE class carries out an experiment to investigate the rate of cooling from 100 °C of a range of hot liquids. Copy out any of the following variables that are likely to have a significant effect on the temperature readings. (You may copy one, two, or all three of the suggested variables.)

type and size of container

volume of liquid

temperature of the surroundings

b. In an experiment to find the resistance of a wire, the students record the current in the wire and the potential difference across it. They then calculate the resistance. Copy out any of the following variables that are likely to have a significant effect on the current and/or potential difference readings. (You may copy one, two, or all three of the suggested variables.)

atmospheric pressure

temperature of the wire

length of wire

c. In an experiment, a short pendulum oscillates rapidly. A student is asked to find the period of oscillation T of the pendulum using a stopwatch. The student sets the pendulum swinging and records the time for one oscillation. A technique for improving the accuracy of the value obtained for the period T should be used in this experiment. State, briefly, what this technique is and any calculation involved to obtain the value of T.