This podcast provides a walkthrough of an AQA AS-level Physics past paper, covering multiple-choice and practical skills questions. The speaker addresses topics such as uncertainties, oscillations, moments, and optics, demonstrating problem-solving strategies and explaining relevant concepts for each question. Throughout the discussion, the speaker clarifies common errors and provides useful tips for students preparing for the exam.
Micrometer Readings
• 00:00:23 The speaker explains how to take a reading from a micrometer, including the main scale and the vernier scale. The reading is determined by combining the main scale and the vernier scale, and is ultimately 6.75 mm.
Ratchet Thimble
• 00:01:26 The purpose of the ratchet thimble in a micrometer is explained. When the ratchet thimble is not used, the user might turn too much and compress the wire being measured, which can lead to inaccurate readings. The gap is closed to prevent the wire from being compressed during measurement.
Percentage Uncertainties
• 00:01:47 The speaker explains how to calculate percentage uncertainty in calculations involving several variables. Using a mass per unit length equation, he demonstrates the addition of percentage uncertainties to achieve a total uncertainty of 4.4%.
Control Variables
• 00:03:13 The speaker identifies two control variables in an experiment with an oscillator. The equation for the frequency of the oscillator helps determine that the length of the wire and the tension, which is related to the mass, should be kept constant.
Inverse Proportionality
• 00:04:11 The speaker illustrates how to check if two variables are inversely proportional using data from a graph. He explains that if the variables are inversely proportional, the product of the values should remain constant. In this case, the frequency and diameter data suggest an inverse relationship, as their product stays relatively constant.