76. Consider the following operation in respect of Wheatstone bridge (Kb, denotes battery key, Kg denotes galvanometer key) open Kbclose Kgclose Kbopen Kg The correct sequence of operations is
77. Two voltmeters 0-250 V each having resistances of 5 kΩ and 10 kΩ respectively and are connected in series. To ensure that neither of them goes beyond scale the total voltage which can be applied should be less than
78. A 24 mm long conductor has a resistance of 128 Ω. The change in resistance is 13.3 Ω and change in length is 1.6 mm under tension. The gauge factor is
79. Measuring of unknown voltage with a dc potentiometer loses its advantage of open circuit measurement when
80. In a digital measuring device the input electrical signal is in the frequency range of dc to ac (50) Hz. It must be sampled at a rate of
81. A meter has a square law scale. For 2 A current the deflection in 90°. For a deflection of 45°, the current is
82. Consider the following Statements regarding resistance strain gauge The gauge factor is in the range of 2 to 5.The resistance changes due to change in specific resistance with strain.The resistance increases with increase in temperature. Of the above statements, which are correct?
83. PCM employing 4 bit code is used to send data having frequency range from 0 to 2 kHz. The minimum required bandwidth of carrier channel is
84. A sinusoidal ac voltage of amplitude 100 V is applied to a rectifying device which offers 10 Ω resistance in forward direction and infinite resistance in reverse direction. The reading on hot wire ammeter will be
85. When a capacitor is connected to the terminals of an ohmmeter, the pointer indicated a low resistance initially and finally come to infinity position. This shows that capacitor is
86. If eddy current damping is to be used, the disc of instrument should be
87. The scale of moving iron instrument is linear.
88. With a variable reluctance tachometer having 60 rotor teeth the count reads 3600 counts per minute. The speed in RPM is
89. When measuring phase angle between two waves using a CRO, the time base generator is connected to
90. It is required that a strain gauge has gauge factor of 100. The proper strain gauge is
91. A meter having 0-1000 μA range and 1000 Ω resistance is required to be changed to 0-100 mA meter. The value of shunt resistance is about
92. An induction wattmeter can be used for
93. In the balanced bridge shown in figure. X should be
94. If the current in a capacitor leads the voltage by 80°, the loss angle of capacitor is
95. In an induction wattmeter, the shading bands are made of non conducting material.
96. The current in a circuit is measured using a 150 : 1 CT If the ammeter reads 0.6 A, the circuit current is
97. A volt ratio box should have low resistance.
98. A Hall effect transducer has KH = - 1 x 10-8. If B = 1 Wb/m2, I = 3 A and bismuth slab is 2 mm wide, the Hall voltage is
99. Two ammeters A and B both 0-10 A have internal resistance of 1 Ω and 0.5 Ω respectively. They are connected in parallel. If total current is 15 A, then
100. The loss of charge method can be used to measure