Athin disk with a circular hole at its center, called an annulus, has inner radius r1 and outer radius r2. the disk has a uniform positive surface charge density σ on its surface.

The answer is a i think

Answerlosing electrons;

The correct option is this: the sound waves from the two trombones have slightly different frequencies.from the question given above, we are told that the loudness of the sounds were increasing and decreasing, this is because the frequencies of the two sounds are different. the means that the number of waves that pass a fixed point in a given amount of time differ for both sounds.