The requested transformer has a 480 turn primary coil and reduces the voltage from 880 V to 220 V. We can use this information to determine the transformer's turn ratio and the number of turns in the secondary coil.

To solve for the turn ratio (N2/N1), we can use the formula: N2/N1 = V1/V2, where N1 is the number of turns in the primary coil, V1 is the input voltage, N2 is the number of turns in the secondary coil, and V2 is the output voltage.

Plugging in the given values, we have: N2/480 = 880/220. Solving for N2, we get N2 = 120 turns.

Therefore, the transformer's turn ratio is 120:480, or 1:4. This means that for every one turn in the primary coil, there are four turns in the secondary coil.

Now, to determine the number of turns in the secondary coil on the open circuit, we can use the formula: V1/V2 = N1/N2, where N1 is the number of turns in the primary coil, V1 is the input voltage, N2 is the number of turns in the secondary coil, and V2 is the open circuit voltage (no load).

Since the transformer is working on the open circuit, we know that the output (V2) is equal to the secondary winding's induced emf. This means that V2 is equal to the open circuit output voltage.

Plugging in the values, we have: 880/220 = 480/N2. Solving for N2, we get N2 = 192 turns.

Therefore, the number of turns in the secondary coil on the open circuit is 192 turns.

Overall, the transformer's turn ratio is 1:4 and the number of turns in the secondary coil on the open circuit is 192 turns.