Which of the following gives materials in order of decreasing values of permeability ?
Answer
Cobalt, Nickel, Aluminium, Iron
Permalloy, Nickel, Air, Water
Silver, Copper, Aluminium, Iron
Pure iron, Silicon iron. Aluminium, Bismuth.
Question 2
Question
In electrical machines the material preferred for pole shoes of electro-magnets is
Answer
Pure iron
Aluminium
Copper
Lead.
Question 3
Question
If the resistivity of aluminium is 0.0283 x 10-6 Ω-m, the resistivity of copper could be
Answer
0.017 x 10-5 Ω-m
0.0382 x 10-5 Ω-m
0.0832 x 10-6 Ω-m
0.0889 x 10-6 Ω-m
Question 4
Question
Three moving iron type voltmeters are connected as shown below. Voltmeter readings are V, V and V 1 2 as indicated. The correct relation among the voltmeter
readings is
The input impedance of the permanent magnet moving coil (PMMC) voltmeter is infinite. Assuming that the diode shown in the figure below is ideal, the reading of the voltmeter in Volts is