To determine the period and frequency of sound waves, we need to understand their definitions and the relationship between them.
1. Period: The period of a wave is the time it takes for a complete cycle to occur. In this case, the sound waves pass a detector every ½ second. Therefore, the period is ½ second.
2. Frequency: The frequency of a wave is the number of cycles that occur in one second. It is measured in units of Hertz (Hz). In this case, the sound waves pass a detector every ½ second. To calculate the frequency, we can take the reciprocal of the period. In other words, the frequency is 1 divided by the period.
Now, let's evaluate the options:
A) The period is 2 s, and the frequency is 2 Hz.
The period stated here is 2 seconds, which contradicts the given information of the sound waves passing the detector every ½ second. Therefore, this option is incorrect.
B) The frequency is ½ second, and the period is 2 Hz.
The frequency stated here is given in seconds, which should be in Hertz. Additionally, the period stated here is in Hz, which is incorrect. Therefore, this option is also incorrect.
C) The period is ½ second and the frequency is ½ Hz.
The period stated here is correct (½ second), but the frequency is given as ½ Hz. Since the frequency should be the reciprocal of the period (1 divided by ½), it should be 2 Hz. Therefore, this option is incorrect.
D) The period is ½ second, and the frequency is 2 Hz.
This option correctly states that the period is ½ second and the frequency is 2 Hz. Therefore, this option is correct.
Therefore, the correct choice is: The period is ½ second, and the frequency is 2 Hz.