When two alternating quantities of the same frequency have different zero points, they are said to have a phase difference. The angle between zero points is the angle of phase difference φ.
In the above-given question, the frequency of voltage and current is different so we can’t calculate the phase difference between them
Air friction Damping: An air friction damping device is usually provided with moving iron instruments such as voltmeters and ammeters.
In this device, a light aluminum vane is attached to a spindle as shown in Fig.
and this vane is free to move in a fixed air chamber known as a sector. When the pointer deflects, the vane in the sector also moves. The air in the sector produces friction in the movement of the vane and thus necessary damping torque is obtained.
Eddy Current Damping: It is used in a strong operating field e.g., PMMC (Permanent Magnet Moving Coil instrument) type.
Fluid Friction Damping: Used in high voltage measurement. Used in the vertically mounted instrument. e.g., Electrostatic type instrument.
A phase sequence is an order or sequence in which the currents or voltages of different phases attain their maximum values. In a three-phase system, there are only two possible phase sequences: R-Y-B (positive Phase Sequence) and R-B-Y (Negative Phase Sequence).
Voltage Scale Span of instrument = Vmax − Vmin
Vmax = 5 V
Vmin = −5V
Span = 5 −(−5) = 10 V