Q.1
A rectifier type AC voltmeter consists of a series resistance R, an ideal full-wave rectifier bridge and a PMMC instrument. The internal resistance of the instrument isΩ and a full- scale deflection is produced by a DC current of 1 mA. A voltage ofV (rms) is applied to the input terminals. The value of R required is?
  • a) 63.56 Ω
  • b) 89.83 Ω
  • c) 89.83 kΩ
  • d) 141.3 kΩ
Q.2
A moving iron ammeter produces a full-scale torque ofμN-m with a deflection ofat a current ofA. the rate of change of self-inductance (μH/rad) of the instrument at full scale is?
  • a) 2.0 μH/rad
  • b) 4.8 μH/rad
  • c) 12.0 μH/rad
  • d) 114.6 μH/rad
Q.3
A moving coil of a meter hasturns and a length and depth ofmm andmm respectively. It is positioned in a uniform radial flux density ofmT. The coil carries a current ofmA. The torque on the coil is?
  • a) 0.0216 N-m
  • b) 0.0456 N-m
  • c) 0.1448 N-m
  • d) 1 N-m
Q.4
TwoμA full-scale PMMC meters are employed to construct aV and aV full-scale voltmeter. These meters will have figure of merit (sensitivities) as?
  • a) 10 kΩ/V and 10 kΩ/V
  • b) 100 kΩ/V and 10 kΩ/V
  • c) 10 kΩ/V and 100 kΩ/V
  • d) 10 kΩ/V and 1 kΩ/V
Q.5
A PMMC rated asμA is used in a rectifier type of instrument which uses full wave rectification. What is the sensitivity on sinusoidal AC?
  • a) 4.5 kΩ/V
  • b) 18 kΩ/V
  • c) 10 kΩ/V
  • d) 9 kΩ/V
Q.6
The discharge of a capacitor through a ballistic galvanometer produces a damped frequency of 0.Hz and successive swings ofand 76.8 mm. The damping ratio is?
  • a) 0.0568
  • b) 0.0887
  • c) 0.0357
  • d) 0.0441
Q.7
The discharge of a capacitor through a ballistic galvanometer produces a damped frequency of 0.Hz and successive swings ofand 76.8 mm. The logarithmic decrement is?
  • a) 0.225
  • b) 0.565
  • c) 0.484
  • d) 0.7887
0 h : 0 m : 1 s