[问答题]
List the three ways t8h sq,5ab0ytbo, jy8,gc ugq/a 2(uholu+pffwvw/ql3//xmd24px p3 t . kl8 rhat an $emf$ can be induced in a loop of wire.
参考答案: 1. by changing the magnetic field
2. by changing the area of the loop in the field
3. by changing the loop's orientation with respect to the field
