Ques.41. Which of the following is the dimension of resistance?
- [M L2 T -3 A-2]✓
- [M L2 T -2 A⁻1]
Firstly consider the resistance.
Ohm’s law states that electric current flowing through the conductor is directly proportional to the potential difference between its two ends when the temperature and other physical parameters of the conductor remain unchanged.
V = IR
⇒ R = VI
Now V has units of (electric field)*(distance).
But the electric field has units (force)/(charge).
Also, charge has dimensions of (current)(time) and force has dimensions (mass)(length)/(time)^2.
Thus, dimensions of V is,
[V] = LMLT−2 ⁄ AT
⇒ [V] = M L² T ⁻³ A⁻¹
Dimensional formula for I = A
Put these values in equation (1), we get:
The dimensional formula for R = M L2 T−3 A−1/ A
Dimensional formula for R = [M L2 T −3 A−2]
Ques.42. A factory runs in 3 shifts of 8 hours each, in which it consumes 30 kW, 15 kW, and 25 kW respectively. Calculate the energy consumed by the factory per day.
- 186.67 kW
- 373 kW
- 560 kW✓
- 746.67 kW
Ques.43. In two wattmeter method of power calculation of 3-phase balanced star connected system, what is the power factor of the system if one of the wattmeters shows zero reading and the other shows a positive reading?
- Greater than 0 but less than 0.5
- Greater than 0.5 but less than 1
Ques.44. Which of the following is NOT an advantage of PMMC type Instrument?
- The frictional error is low✓
- Single Instrument can be used for multirange measurement of voltage and current
- Uniformly divided scale
- Stray magnetic field error is small
Ques.45. Which of the following can measure the resistance having the value below 1 Ohms most precisely?
- Kelvin’s Double Bridge✓
- Wheatstone Bridge
Ques.46. Which of the following quantities cannot be measured using a multimeter?
- AC voltage
- DC Current
- Phase Angle✓
Ques.47. Which of the following materials when used as the viewing surface of a CRO gives a bluish glow?
- Zinc Sulfide with copper as Impurity
- Zinc sulfide with silver as Impurity✓
- Yttrium Oxide
- Pure Zinc Sulfide
Ques.48. What is the percentage voltage error of a potential transformer with the system voltage of 11,000 V and having turns ratio of 100, if the measured secondary side voltage is 105 V?
Ques.49. Which of the following is the cause of the speed error in the induction type energy meter?
- Incorrect Position of brake magnets✓
- Incorrect adjustment of the position of shading bands
- Slow but continuous rotation of an aluminum disc
- Temperature variations
Ques.50. A circuit having the power factor of 0.8 consumes 20 W. What is the value of reactive power (in VAR) of the circuit?