Alexandra knows that the atomic number of the element potassium, k, is 19. she also knows that one particular isotope of potassium has a mass number of 39. how many neutrons can be found in the nucleus of this isotope of potassium?

a) 19

b) 20

c) 39

d) 58

Avery long solenoid of inner radius 2.75 cm creates an oscillating magnetic field of the form = for this solenoid, =0.00425 t and =319 rad/s. (a)what is the maximum value of the induced electric field at a perpendicular distance 1.45 cm from the axis of the solenoid? (b) what is the maximum value of the inducted electric field at a point 5.85 cm perpendicular from the axis of the solenoid?