Question

The uncertainty principle arises from a common-sense idea: To measure something, you must affect it somehow. For instance, when you use a pressure gauge to measure air pressure in a car tire you release a small amount of air into the gauge.

• Why does shining very short wavelength photons on an electron not tell you exactly where the electron is?
• Describe two other examples of situations in which measuring something about an object somehow changes it.

Answer 1

The very short wavelength photons carry very high energy. And when these energetic photons are incident upon the electron, the electron gets energized and moves away and hence it becomes impossible to measure exactly the position of the electron.

Any observation made effects the system in some way. Smaller this system is, more becomes the uncertainty. One example can be taken that of the measurement of the position of electron. If we measure the position of electron accurately then its momentum will become highly uncertain since the act of measurement would have changed its momentum. Similarly if we measure the spin of the electron then all thee quantities will become highly uncertain and the electron would be changed. This is not only limited to electrons instead this is the Case with each and every particle or material body. We just don't notice it in our normal world because the uncertainty caused by the measurement is highly negligible.