Answer process:

By adjusting the P contact, the effective value of the output voltage is reduced from 220V to 1 10V, and the output voltage is reduced to half of the original value. According to Ohm's law, I = U/R, under the condition of constant resistance, the ratio of output current of the secondary coil before and after adjustment is as follows: front I2: rear I2 = front U2: rear U2 = 2:1;

According to the power P=UI, the ratio of output power of the secondary coil before and after adjustment is obtained: after P2 = before UI, before I2, after U2 and after I2 = 4:1;

According to the ideal transformer principle U 1: U2 = n 1: n2, under the condition that the primary coil voltage and turns are unchanged, the access turns of the secondary coil should also be half of the original, and the ratio of access turns before n2: after n2 = before U2: after U2 = 2:1;

The input power of the primary coil is equal to the output power of the secondary coil, so the ratio of the input power of the primary coil is P 1 before: P 1 after = before P2: after P2 = 4: 1.

Hope to adopt!