Final answer:
When turning your head to the left, the cupula in the right semicircular canal deflects in the opposite direction, due to the inertia of the fluid within the canal, triggering the hair cells to send signals indicating head movement to the brain.
Step-by-step explanation:
If you turn your head to the left, the activity in the cupula in your right semicircular canal would show a deflection opposite to the direction of head movement. This happens because the fluid within the semicircular canals lags behind due to inertia. As a result, the movement of the fluid bends the cupula and stereocilia within the ampulla, which in turn stimulates the hair cells to send signals to your brain, indicating the head has turned.
The right semicircular canals would be stimulated because they detect rotational movements in the plane in which the head turns.