Lianyungang medical equipment transformer manufactory

The primary coil voltage u = 311sin100 π t (v), which shows that the effective voltage of the primary coil is 220V, so the indicated value of voltmeter V 1 is about 220V, so A is wrong;

According to the voltage is proportional to the number of turns, and the ratio of turns of primary and secondary windings is 5: 1, it can be known that the effective value of secondary winding voltage is 44V ... Because the resistance r 1 = 20ω, U2=24V, U2 = 24V, the indication of voltmeter V2 is about 24V, so C is wrong.

The effective value of the current in the secondary coil is I2 = ur1+R2 = 4420+24a = 1A, so the current in the primary coil is I1=15×1a = 0.20a, so the indicator of ammeter A2 is about 0.20a.

So choose B.