Orange light of frequency 5 x 1014 Hz, and violet light of frequency 7 x 1014 Hz, both shine on a metal surface whose photoelectric threshold frequency is 6 x 1014 Hz. This will cause the metal surface to emit

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.