Resolution can mean a lot of things outside of physics. You may recognize it from screen size, camera quality, and even making New Year's promises. But in physics, it means something quite specific.

The resolution of a device is the interval between its smallest divisions. A good example is a standard meter stick. The smallest divisions are usually separated by 1 mm, which means that the resolution of a meter ruler is 1 mm. The smallest divisions on a thermometer are usually 1 degree Celsius or Fahrenheit, and so would have a resolution of 1 degree.

This idea also applies to digital devices. The resolution of these devices is one unit of their lowest significant figure. So for a digital scale that reads to the nearest kilogram, its resolution would be 1 kg. This is because the scale would read 1 kg for all values from 0.5 kg up to just below 1.5 kg, giving a range of values 1 kg wide.

Resolution can be a help when choosing an appropriate tool for an experiment. Ask yourself, what is an acceptable uncertainty on your measurement? If you are measuring someone's height, measuring to the nearest millimeter is usually good enough, so a tool with a resolution of 1 mm would be a good fit. Measuring the width of a blood cell would require a device with a higher resolution, and lower associated uncertainty.

Resolution varies a lot from device to device. For example, a measuring tape's resolution is usually 1 millimeter, and an optical microscope's resolution can be as good as 0.2 micrometers. An electron microscope has a resolution of around a tenth of a nanometer.

But a higher resolution isn't always better. It would be poor experimental design to try and measure someone's height with an electron microscope when the trusty meter stick would do the trick! Practicality, cost, and time taken to use are all important factors to consider when designing an experiment. A higher resolution is not always better!