Why would a poet use imagery in a poem?

So the reader can have a visual sense of what the poem says

"as the band marched across the crowd field cheered"

here here are the quiz answers thats all i can do hope i was able to =]    

i see some of you tried the true/false quiz of what was real and what was made up in little women. no one got 100% but you were very close! here are the answers:

hannah the servant  false– the alcotts could not afford any servants in those daysthe christmas play (“the witches’ curse, an operatic tragedy)  true  – this play is actually a composite of actual plays written and performed by louisa and anna.amy burns jo’s manuscript  falsemarmee’s temper  trueamy falling through the ice  falsejo pinching meg’s papered locks before the ball  falsemeg being dressed up as a doll at annie moffat’s  falseamy bewailing her pickled limes  truebeth receiving the piano from mr. lawrence  true  – in harriet reisen’s book louisa may alcott the woman behind little women, lizzie received a piano as a gift in walpole, nh when she was twenty from dr. henry whitney bellows (see chapter 9 in the book)mr. march’s illness  false  – louisa was writing about her own illness her civil war nursing stintjo sells her hair.  false  but it was based on something true, that louisa had all her hair cut off during her illness after the civil warbeth wasted away and died peacefully.  false  lizzie (aka beth) did waste away but she was in tremendous pain, was often quite anxious, and even went through a spell where she rejected her family and wanted to be left alone (anna said in a letter that lizzie had called her “horrid.”)jo published her first story, “the rival painters.”  trueamy writes her own will.  true?   not sure on this one (i know, i shouldn’t have included it if i didn’t know the answer! )jo rejects laurie’s love.  false