Máy biến áp một pha có tiết diện trụ lõi thép là 135cm2, điện áp sơ cấp/thứ cấp là 10kV/0,23kV; tần số của dòng điện xoay chiều là 50Hz. Biết độ cảm ứng từ trong lõi thép là 1,1 T. Tính số vòng cuộn dây sơ cấp, thứ cấp.

Heat is added to a piston-cylinder device filled with 2 kg of air to raise its temperature 400 c from an initial temperature of t1 27 cand pressure of pi 1 mpa. the process is isobaric process. find a)-the final pressure p2 b)-the heat transfer to the air.

Consider a large isothermal enclosure that is maintained at a uniform temperature of 2000 k. calculate the emissive power of the radiation that emerges from a small aperture on the enclosure surface. what is the wavelength ? , below which 10% of the emission is concentrated? what is the wavelength ? 2 above which 10% of the emission is concentrated? determine the wavelength at which maximum spectral emissive power occurs. what is the irradiation incident on a small object placed inside the enclosure?

Aquick transition of the operating speed of a shaft from its critical speed will whirl amplitude. (a) increase (b) limit (c) not affect (d) zero