A 1 MHz carrier signal is modulated by a symmetrical sinusoidal wave for period of 100 μs in a non-linear (square law devices) which of the following frequencies will not present in the modulated signal

The frequency of modulation signal are from non linear devices are fc,  fc±fm,   fc±3fm fc=1 MHz=1000 kHz fm=1T=1100×10-6=10 kHz So, frequency present in AM are 1000 kHz, 990 kHz,   1010 kHz,  970 kHz,  1030 kHz