Q131. In a wave motion, the time required to complete one cycle is called______.

Q132. Coefficient of absorption of sound is measured in _______.

Q133. Unit of frequency is __________.

Q134. SI unit of potential difference is _________.

Q135. When the ray of light enters from rarer to denser or denser to rarer medium, there occurs change in its velocity this is called ________ property of light.

Q136. The frequency of a wave is 100 Hz. So, its periodic time is                 .

Q137. Unit of coefficient of thermal conductivity is __________.

Q138. The capacity to collect the light by optical fiber is called_______.

Q139. What is the primary cause of linear thermal expansion in solids?

Q140. In the formula \(v = n· \lambda \), \(\lambda = \) wavelength, \(v=\) velocity then, \(n=\) ________.