Observation

The expected answers are:

         (a)    Symptoms of a faulty mobile phone microphone

• poor audio quality during phone call / receiver cannot hear the caller’s voice (one way conversation)
• change in sound / callers voice is distorted to the receiver
• sound interruption / receiver can hear the caller on some occasions but not all the time

    
(b)    Components of a mobile phone with polarity

• backup battery
• electrolytic / polarised capacitor
• battery terminal connector
• mouthpiece / microphone
• earpiece / speaker
• vibrator / motor
• buzzer / ringer / loudspeaker
• transistor
• regulator
• charging port
• diode