The correct option is (a).
Explanation
In wave mechanics, the time period refers to the time required to complete one full oscillation or cycle of the wave. It is a fundamental characteristic of both mechanical (e.g., sound) and electromagnetic waves.
Statement-wise Analysis:
- Statement 1 is Correct: The time period is conventionally represented by the symbol T. It denotes the time taken for a particle of the medium to complete one vibration or for the wave to travel a distance equal to one wavelength.
- Statement 2 is Incorrect: The time period (T) and frequency ($\nu$ or $f$) are inversely proportional to each other. The relationship is expressed mathematically as:
$$T = \frac{1}{\nu}$$
As frequency increases, the time period decreases, and vice versa. - Statement 3 is Incorrect: Since the time period is a measure of time, its SI unit is the second (s). Hertz (Hz) is the SI unit of frequency, representing the number of cycles per second.
Key Takeaway:
The time period ($T$) is the reciprocal of frequency ($\nu$). While the SI unit of frequency is Hertz (Hz), the SI unit of the time period is the second (s).