Practical Skills II: Planning (Edexcel International A Level Physics)

A student investigated the relationship between the length l of a column of air and its temperature θ using the apparatus shown.

A sample of air is trapped inside the tube between the closed end and the drop of concentrated sulfuric acid.

Suggest why one end of the tube is left open.

The student suggested placing the apparatus in a beaker of boiling water and allowing the water to cool. Boiling water is a hazard.

Explain one other reason why this method may be hazardous.

The capillary tube was attached to a 30 cm ruler and placed in a beaker of water at room temperature. The water was heated gradually and θ was measured using a thermometer.

i) State two techniques that should be used to ensure the measurement of θ is as accurate as possible.

(2)

ii) The student recorded the following measurements.

The student predicted that a graph of l against θ could be used to estimate a value for θ at absolute zero as shown.

Discuss whether the student’s measurements would lead to an accurate value of θ at absolute zero.

(3)

A student investigated Lenz’s law using the apparatus shown.

The student dropped the magnet into the copper tube and measured the time t for the magnet to reach the bottom of the tube.

The student had a large number of copper tubes of different lengths x. He predicted that the magnet would fall with constant acceleration a inside the copper tubes.

Devise a plan, using a graphical method, to test this prediction.

Explain a possible source of error in this investigation.