Hi, please could someone help with my confusion over these two qauntities. In class we recently learnt that magnetic field strength (B) is the number of flux lines (measured in Webers) per square metre. The magnetic flux on the other hand is the total number of flux lines (measured in Webers), hence the equation for magnetic flux is: Magnetic flux = B A What I don't quite get is why you need to take the dot product with the area vector. Flux is associated with something that penetrates a given surface. But magnetic field strength is webers/square metre therefore it is the number of flux lines per square metre. So don't flux lines by definition already penetrate a surface, hence flux lines per square metre already referes to a magnetic field that is penetrating a surface?