A moving-coil ammeter has a fixed shunt of 0.02 Ω. With a coil resistance of R = 1000 Ω and a potential difference of 500 mV across it. Full-scale deflection is obtained. (a)
To what shunted current does it correspond? (b) Calculate the value of R to give fullscale deflection when shunted current I is (i) 10 A, and (ii) 75 A, (c) With what value of
R, 40% deflection obtained with I = 100 A.

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

The sum of the normal stresses does not change as the stress state rotates through an angle. a)-trune b)- false

The proportional limit is always greater than the yield strength for a material. a)-trune b)- false