# A cylinder of radius R is surrounded by a cylindrical shell of inner radius R and outer radius 2R. The thermal conductivity of the material of the inner cylinder is K1 and that of the outer cylinder is K2. Assuming no loss of heat, the effective thermal conductivity of the system for heat flowing along the length of the cylinder is: a. K1 + K2 b. c. d. ## Question ID - 50615 :- A cylinder of radius R is surrounded by a cylindrical shell of inner radius R and outer radius 2R. The thermal conductivity of the material of the inner cylinder is K1 and that of the outer cylinder is K2. Assuming no loss of heat, the effective thermal conductivity of the system for heat flowing along the length of the cylinder is: a. K1 + K2 b. c. d. 3537 Keq= = = Next Question :

A travelling harmonic wave is represented by the equation y (x, t) = 10–3 sin (50 t + 2x), where x and y are in meter and t is in seconds. Which of the following is a correct statement about the wave?

The wave is propagating along the

a. negative x−axis with speed 25ms–1

b. The wave is propagating along the positive x-axis with speed 25 ms–1

c. The wave is propagating along the positive x-axis with speed 100 ms–1

d.  The wave is propagating along the negative x-axis with speed 100 ms–1 