We have two noise generators: one gives 3 the other 4 V effective voltage. We form a new generator by connecting them in serial arrangement. Then the resultant voltage is 7V. How will this voltage change when we reverse the 4 V generator's polarity?

The correct answer is - 1

Explanation:

As it has been mentioned that the generators are connected in serial arrangement so tha resultant voltage is + 3V+4V=7V. Later it is mentioned that the polarity of 4V generator has been reversed which means - 4V+3V = - 1V

Hence the resultant voltage is - 1.