Synchronous speed ($N_s$) depends directly on supply frequency ($f$) and inversely on the number of stator poles ($P$).

Slip at full load for standard industrial induction motors typically ranges from 2% to 5%.

At standstill condition ($N = 0$), the slip value $s = 1$ or $100\%$.

Frequency of rotor currents is given by $f_r = s \cdot f$, which equals $2.5\text{ Hz}$ in this case.

Simple calculation method based directly on motor shaft speed and supply parameters.

Slip value directly indicates rotor electrical frequency and rotor copper losses.

Higher slip values lead to lower efficiency due to higher rotor $I^2R$ losses.

Calculations assume ideal line frequency without supply harmonic deviations.

Determining motor load condition and torque production in industrial drives.

Calculating rotor parameters such as rotor frequency ($f_r$), rotor induced EMF ($E_{2r}$), and rotor reactance ($X_{2r}$).

Option A (1%) is incorrect because it would correspond to a rotor speed of $990\text{ rpm}$.

Option C (3%) is incorrect because it corresponds to a rotor speed of $970\text{ rpm}$.

Option D (10%) is incorrect as it corresponds to a rotor speed of $900\text{ rpm}$.