A frequency generator in the school laboratory can be adjusted from 5Hz to 50kHz and is connected to a loudspeaker.
(i) Calculate the time period corresponding to the frequencies 10Hz, 2kHz, and 40kHz. Express your answers in seconds using scientific notation.
(ii) For each of the three frequencies in part (i), state whether the sound produced is infrasonic, audible, or ultrasonic to an average human.
(iii) A pet dog in the laboratory begins to bark continuously when the frequency knob crosses 25kHz. Explain this observation with reference to the animal’s range of hearing.