81. Write the unit of surface tension in SI system.
82. Which physical quantity has unit of pascal - second ?
83. Which physical quantity has unit of joule - second ?
84. What is the least count of vernier calipers ?
85. What is the least count of screw gauge ?
86. For measurement of astronomical distance ________ is used.
87. Which microscope is used to measure the dimension of particle having dimension less than \(4000 \dot{A}\) ?
A. electron microscope
B. simple microscope
C. optical microscope
D. none of above
Answer : Option A
88. In electron microscope electron behave like ________
89. Which wave length of light is used in an optical microscope ?
90. The intercepted area of the spherical surface about the center is \(0.25m^{2}\) having diameter \(50cm\) what will be solid angle ?
A. \(4\times 10^{-1}Sr\)
B. \(1\times 10^{3}Sr\)
C. \(10^{-1}Sr\)
D. \(5\times 10^{-1}Sr\)
Answer : Option A
Explanation :
\(\Delta A=0.25m^{2}\)
\(2r=0.5m\)
Solid angle \(=\frac{\Delta A}{r^{2}}=0.4\ Sr\)
\(=4\times 10^{-1}Sr\)