I am new to reinforcement learning, i have studied about its basics and principles, however, i have one question:

If I implemented q-learning to a robot, for example, to make my robot learn to navigate around the house to pick up a ball, then the optimal policy for the robot in that house is found

If i am to change the environment, such as, moving the ball to another place, change the place of my furniture, or make the robot find a ball in my friend's house instead

Can the robot adapt to the new environment, and how fast will it be? Thank you

The encoding of the state of the environment can be critical. For example, if you encode the state as the $(x,y)$ coordinate position of the robot, then it will not adapt at all when you change the position of the ball. This is because the Q-value of the original position of the ball was probably quite high, but by moving the ball, you have completely changed the Q-values of the game, and using the old Q-values will not make sense.