Measuring Variables (Edexcel International A Level (IAL) Physics): Revision Note

Exam code: YPH11

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Katie M

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Measuring Variables

  • When measuring a variable in an experiment, it is important to use the most appropriate instrument and measuring technique to achieve the most accurate value for that measurement

  • A list of the common apparatus and their purpose is shown in the table below:

Apparatus and Their Purpose Table

Experimental Instrument

Purpose

Example

Metre ruler

To measure the length of an object of a length between 1 cm - 1 m

Length of a wire

Vernier Calipers

To measure short lengths between 0.1 mm - 1 cm

Extension of a wire

Micrometer Screw Gauge

To measure very short lengths between 0.01 mm – 0.1 mm

Diameter of a wire

Top-pan Balance

To measure the mass of an object

Weight of a block

Protractor

To measure angles

Measuring angle of refraction of a beam of light

Stopwatch

To measure time

Time taken for an oscillation

Thermometer

To measure temperature

Temperature increase for specific heat capacity of a material

Voltmeter

To measure potential difference

Potential difference across a bulb

Ammeter

To measure current

Current through a bulb

Oscilloscope

To display waves and measure their frequencies

Frequency of a signal

Laser

To provide a monochromatic, coherent source of light

Investigating the interference of light

  • The key factor associated with choosing the appropriate instrument is its resolution

    • If the resolution of an instrument is too big, then it won't be able to measure small measurements

Examiner Tips and Tricks

When planning experiments, make sure to really think about which instrument you need to measure the length of something. A rough rule could be:

  • Length will be between a few cm – 1 cm, use a ruler

  • Length will be between 0.1 mm – few cm, use a vernier caliper

  • Length will be between 0.01 mm – 0.1 mm, use a micrometer

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Katie M

Author: Katie M

Expertise: Physics Content Creator

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.