The circuit shown is designed to test reaction time.

The following instructions will test the reaction time of a student.
● Hide switch S1 from the student.
● Move S1 to position 1 and wait until the voltmeter reads 6.0 V.
● Close switch S2.
● At a random time, move S1 to position 2 so the buzzer sounds.
● As soon as the buzzer sounds, the student should open S2.
● Use the new voltmeter reading to calculate the student’s reaction time.