There are a few potential reasons why your phone charger is making a high frequency sound. One possibility is that it is due to the internal components of the charger vibrating at a high frequency. This can happen when the charger is converting the AC current from the wall outlet into the DC current that is needed to charge your phone. The process of converting the current can create small vibrations within the charger, which can produce a high pitched sound.
Another potential cause could be electromagnetic interference (EMI). This occurs when the electrical signals within the charger interact with other electronic devices or components, causing them to vibrate and produce sound. This can be more noticeable when your phone is plugged in and drawing power from the charger, as it can create more electrical activity and potential for interference.
Additionally, it is also possible that the sound is being produced by a faulty or damaged component within the charger. If this is the case, it is important to stop using the charger and have it checked by a professional to avoid any potential safety hazards.
Overall, the high frequency sound from your phone charger is likely due to the internal components vibrating or EMI, which are common occurrences in electronic devices. However, if the sound becomes louder or more frequent, it is recommended to have the charger inspected to ensure safe and proper functioning.