A long cylindrical iron core of cross-sectional area 5 cm2 is inserted into a long solenoid having 4000 turns/meter and carrying a current 5 A. The magnetic field inside the core is $$\pi$$ T. Find the pole strength developed.
A plane requires for take off a speed of 72 kmh$$-$$1, the run on the ground being 50 m. The mass of the plane is 10000 kg and the coefficient of friction between the plane and the ground is 0.2. Assume that the plane accelerates uniformly during take off. The minimum force required by the engine of the plane for take off is
Given that in a fluorescent lamp's choke, a reverse voltage of 120 V is generated as the choke's current changes steadily from 0.50 A to 0.20 A in a time frame of 0.030 ms. Calculate the self inductance of the choke in millihenrys (mH).
If a man becomes a giant, expanding his linear dimensions by a factor of eight, and assuming his density remains unchanged, the factor by which the stress in his legs will increase is