I don't completely understand how equation 4.4.4 was derived and determined. I understand the derivation behind the basic wave equation 4.3.4 but not what happened in 4.4.4. Why is there a need for all the negative signs ? Would a simple phase change suffice ?
Please do be a bit detailed in your explanation.... Pretend I'm an idiot. Thank you !
Attachment 57535
Please do be a bit detailed in your explanation.... Pretend I'm an idiot. Thank you !
Attachment 57535