In "To Kill a Mockingbird", how does Jem react when Atticus tells him to go home, and why?

In this chapter, the children, lead by Jem,  sneak out of their house and follow their father to the center of town.  There, an angry mob of people from town approach Atticus.  They tell him to move away from the jailhouse door, but Atticus refuses.   At this point Scout comes out of her hiding place in an effort to help her father and Jem and Dill follow her. The mob says Atticus has 15 seconds to make his children leave, but they refuse. They stay to help their father.  He disobeys his father, but does so in a more mature manner.  Jem is becomming more of an adult at this point in the novel.   Jem tries to "break the tension" by telling his father that the "phone is ringing".  He fully understands and is aware of the difficult situation his father is in defending Tom Robinson.   He fears for his father's safety. Scout also plays an important role as she picks out Walter Cunningham in the crowd and has a conversation with him.