Answer:
B) a louder sound of the same pitch.
Step-by-step explanation:
Given that the loudspeaker produces a sound wave of frequency 50hz and the amplitude of the sound wave is increased.
As loudness of the sound depends on the amplitude of the sound while pitch depends on the frequency of the sound.
On increasing the amplitude of the sound there is no effect on the frequency of the sound, so, the loudness of the sound will increase while the pitch remains unchanged.
Therefore, on increasing the amplitude of the soundwave a louder sound of the same pitch is heard.
Hence, option (B) is correct.