It is true that carpets and curtains/drapes placed on the floor or wall surfaces can reduce noise level. Explain briefly?

Friction can be reduced by making a surface rough. true/ false

Sketch a graph between frequency of incident radiations and stopping potential for a given photosensitive material. What information can be obtained from the value of the intercept of potential axis? A source of light of frequency of greater than the threshold freuency is placed at a distance of 1 m from the cathode of a photocell? the distnace of hte light sources from the cathode is reduced explain giving reasons, what change will you observe in the Stopping potential.