If a 10 pH inductor and a 50 pH inductor are connected in series, the total inductance of the resulting circuit is
A. 60 HH.
| B. 40 4H.
C. 7.6 H.
D. 9.8 JH

Asolid cylinder is concentric with a straight pipe. the cylinder is 0.5 m long and has an outside diameter of 8 cm. the pipe has an inside diameter of 8.5 cm. the annulus between the cylinder ad the pipe contains stationary oil. the oil has a specific gravity of 0.92 and a kinematic viscosity of 5.57 x 10-4 m2/s. most nearly, what is the force needed to move the cylinder along the pipe at a constant velocity of 1 m/s?