How does Tiny Tim represent society in Scrooge's time?

Tiny Tim represents the working-class people of London in the early 1800s. During the early 1800s, the Industrial Revolution was beginning to transform English society. One aspect of this transformation was the amount of people from rural areas and small towns who arrived to cities, such as London, in search of work as the English economy moved away from an agriculturally centered society. Working-class people in London often worked twelve- to sixteen-hour shifts in factories in incredibly harsh conditions. Factory owners were able to make great profit through the exploitation and low pay of their workers. While Scrooge is not a factory owner, he certainly exploits his workers in a similar fashion. Tiny Tim's father, Bob Cratchit, is employed by Scrooge and is paid minuscule wages. However, because so many company owners could pay horrible wages because of a lack of labor laws, Bob is unable to secure better wages. His son Tiny Tim is very sickly, and the Cratchits can not afford to provide him with decent health care. Scrooge could certainly afford to pay Bob much better wages and, as such, ensure that Tiny Tim survives. Tiny Tim's suffering at the hands of an exploitative capitalist boss is certainly a reflection of the suffering of the working-class people of the 1800s in England (and much of the industrializing world).

In A Christmas Carol, Tiny Tim represents the importance of charity in Scrooge's Victorian society. Tiny Tim is the son of Scrooge's employee, Bob, and suffers from a medical condition which has left him crippled and weak. In Stave Three, Tim is portrayed as a kind-hearted and humble little boy with a strong sense of Christian morality, as we see through his father's observations:

"He(Tiny Tim) told me, coming home, that he hoped the people saw him in the church, because he was a cripple, and it might be pleasant to them to remember upon Christmas Day who made lame beggars walk and blind men see.”

Because of the poverty his family endures, Tiny Tim's future seems doomed by the prospect of a premature death, as we see in the fourth stave. But in the final stave, Tim is saved by the charity and friendship of the reformed Ebeneezer Scrooge who becomes a "second father" to him.
By portraying Tim in this way, Dickens evokes great sympathy for his character and ensures that  middle-class readers are moved by the challenges and burdens of his life. It is important to note that Dickens did this deliberately: he wanted to encourage his readers to realise that their charity and compassion were essential in combatting the problem of poverty.