Class 12 Physics Question Paper 2080
Group - B
Class 12 Important Physics Question Paper 2080
Give short answers to the following questions.
[8 x 5 = 40]
12. a) Define the coefficient of viscosity. Discuss the effect of temperature on the viscosity of liquid and gas. [1+1]
b) Eight spherical raindrops of equal size are falling vertically through the air with a terminal velocity of 0.15 m/s. What would be the terminal velocity if these two drops were to coalesce to form a larger spherical drop? [2]
c) Roofs of the huts are blown up during storm NWhy?
[1]
OR
[1]
a) What is the "surface energy density" of liquid.
b) Establish the relation between surface tension and surface energy density of a liquid. [2]
c) Calculate the height to which water will rise in a capillary tube of 1.5 mm diameter assuming zero angle of contact. The surface tension of water is 7.4 x 10-3Nm-1.
13. a) Derive an expression for the total mechanical energy of a particle executing simple harmonic motion.
[2] b) Show graphically, how the kinetic energy, potential energy and total energy of the particle vary with displacement from its equilibrium position. [1] c) A body of mass 2kg is suspended from a spring of negligible mass and is found to stretch the spring 0.1m. What is its force constant and the time- period? [2]
14. a) Obtain an expression for the magnetic field at a point due to a current carrying a long straight conductor using Biot-Savart law. [3]
b) A copper wire has 10 29 free electrons per cubic meter, a cross-sectional area of 2 mm2 and carries a current of 5A. Calculate the force acting on each electron if the wire is now placed in a magnetic field of flux density 0.15 T which is perpendicular to the wire. [2]
