I'm in my first year of PhD, but sometimes I forget basic things that I have learned in my undergraduate years. I have a masters but my masters was general not specific, and now I'm working in a specific topic in the PhD. My PhD is in the field of piezoelectricity and I have forgotten information that I studied before in Electromagnetism. I am now finding myself watching lectures for undergraduate students, but its not that bad, it doesn't take me much time to understand. But then, I get more questions in my head as I explore more and more information, and then more time passes before finishing what my supervisor told me to study.

Is this normal, or does it mean that I'm not ready for PhD? So when PhD students start their PhD, and start doing literature review, do they also review material studied before?

I'm in my first year of PhD, but sometimes I forget basic concepts that I have learned in my undergraduate years. I have a masters but my masters was general not specific, and now I'm working in a specific topic in the PhD. My PhD is in the field of piezoelectricity and I have forgotten information that I studied before in Electromagnetism. I am now finding myself watching lectures for undergraduate students, but its not that bad, it doesn't take me much time to understand. But then, I get more questions in my head as I explore more and more information, and then more time passes before finishing what my supervisor told me to study.

Is this normal, or does it mean that I'm not ready for PhD? So when PhD students start their PhD, and start doing literature review, do they also review material studied before?

By the way, I also think that I have maladaptive daydreaming, so this makes things worse. :(