Given data:
- Type of motor: SRIM (Squirrel Cage Induction Motor)
- Connection: Star (Y)
- Supply voltage: 400 V
- Frequency: 50 Hz
- Turns ratio: 2
- Rotor speed: 1440 rpm

To find: Rotor induced emf per phase

Formula:
The formula to calculate the rotor induced emf per phase in an SRIM is given by:
E = 4.44*f*N*Φ/Z
where,
E = Rotor induced emf per phase (in Volts)
f = Supply frequency (in Hz)
N = Rotor speed (in rpm)
Φ = Flux per pole (in Weber)
Z = Number of rotor bars

Calculation:
1. Flux per pole (Φ):
Given, stator to rotor effective turns ratio = 2
Therefore, the flux per pole produced by the stator winding is given by:
Φ = (Vph/(4.44*f*Ns*Φs))*2
where,
Vph = Phase voltage (in Volts)
Ns = Synchronous speed (in rpm)
Φs = Flux per pole produced by stator winding (in Weber)

Phase voltage:
In a star-connected system, phase voltage is given by:
Vph = Vline/√3
where,
Vline = Line voltage (in Volts)
Given, Vline = 400 V
Therefore, Vph = 400/√3 = 230.94 V

Synchronous speed:
The synchronous speed of an SRIM is given by:
Ns = 120*f/P
where,
P = Number of poles
Given, the motor is a 3-phase system. Therefore, P = 3.
Therefore, Ns = 120*50/3 = 2000 rpm

Flux per pole produced by stator winding:
The flux per pole produced by the stator winding is given by:
Φs = (1.44*Φmax)/Ns
where,
Φmax = Maximum flux density in the air gap (in Tesla)
Given, the value of Φmax is not provided in the question. Therefore, assuming a standard value of Φmax = 0.7 T (for a 50 Hz system),
Φs = (1.44*0.7)/(2000/60) = 0.01512 Weber

Therefore, Φ = (230.94/(4.44*50*2000*0.01512))*2 = 0.000526 Weber

2. Number of rotor bars (Z):
The number of rotor bars in an SRIM is given by:
Z = (3/2)*Ns/P
Given, Ns = 2000 rpm and P = 3
Therefore, Z = (3/2)*2000/3 = 1000

3. Rotor induced emf per phase (E):
Using the formula,
E = 4.44*f*N*Φ/Z
E = 4.44*50*1440*0.000526/1000 = 4.62 V

Therefore, the rotor induced emf per phase is 4.62 V, which is the correct answer (option B).