.To demonstrate the phenomenon of beats we need*1 point(a) Two sources which emit radiation of nearly the same frequency(b) Two sources which emit radiation of exactly the same frequency(c) Two sources which emit radiation of exactly the same frequency and have a definite phase relationship(d) Two sources which emit radiation of exactly the same wavelengt

To demonstrate the phenomenon of beats, we need:

(a) Two sources which emit radiation of nearly the same frequency

The phenomenon of beats occurs when two sound waves of slightly different frequencies interfere with each other. The interference of these two waves leads to variations in volume, known as beats. The beat frequency is equal to the absolute difference between the two frequencies.

For example, if two sound waves with frequencies of 440 Hz and 442 Hz interfere with each other, the beat frequency will be 2 Hz. This means you would hear two beats per second.

So, the correct answer is (a) Two sources which emit radiation of nearly the same frequency. The other options are not correct because having exactly the same frequency or wavelength would not result in the creation of beats. A definite phase relationship is also not necessary for the creation of beats.