Barbara Hackett, 50, of Richmond Grove, Bexhill, was turning into Beeching Road when the accident happened.
Prosecutor Mark Kateley said: "The defendant was travelling in a westerly direction in Bexhill town centre. She went to turn right into the other road and the car cut across the path of a moped being driven by a 17-year-old man.
"He had to brake sharply and due to the road being damp he lost control of his moped.
"The 17-year-old sustained minor injuries to his left leg.
"The defendant was interviewed and she said she indictated to turn right into Beeching Road and did not see any other vehicles."
Hackett appeared before Hastings magistrates on Monday and pleaded guilty to one charge of careless driving.
The incident happened on September 24 last year.
Representing herself, Hackett said: "I would like to apologise to everyone concerned, particularly to the moped rider. I did not see him.
"It was wet and dark at the time and I was not driving particularly fast."
Magistrates fined Hackett 135 and ordered 35 costs. They also put three penalty points on her licence.