2500 V
Step 1: Use the transformer equation \( \frac{V_s}{V_p} = \frac{N_s}{N_p} \), where \( V_s \) and \( V_p \) are the secondary and primary voltages, and \( N_s \) and \( N_p \) are the number of turns in the secondary and primary coils, respectively.
Step 2: Substitute the known values: \( \frac{2000}{100} = \frac{V_s}{50} \).
Step 3: Solving for \( V_s \) gives \( V_s = 20 \times 50 = 1000 V \).
Step 4: Thus, the potential difference across the secondary is 1000 V.