Why do transformers hum?

Why is Power Factor of Transformer is Poor at no Load?

5 transformer fault conditions and how to protect from them | EEP

Power Transformer Protection

Power Transformer & Distribution Transformer | Electrical4u

The reason for hum sound during operation of a transformer.... | Filo

31 practical do’s and don’ts to avoid loud transformer humming | EEP

Stop Transformer Noise With These Rules and Techniques | EEP