QUES: Since the armature windings of a direct-current or universal motor are moving through a magnetic field, they have a voltage induced in them. This voltage tends to oppose the motor supply voltage and so is called "back electromotive force (emf)". The voltage is proportional to the running speed of the motor. The back emf of the motor, plus the voltage drop across the winding internal resistance and brushes, must equal the voltage at the brushes. This provides the fundamental mechanism of speed regulation in a DC motor. If the mechanical load increases, the motor slows down; a lower back emf results, and more current is drawn from the supply. This increased current provides the additional torque to balance the new load.
Voltage opposing the motor supply voltage is called what?

ANS: back electromotive force

QUES: At present, the full name of the government of Nanjing is "People's Government of Nanjing City" and the city is under the one-party rule of the CPC, with the CPC Nanjing Committee Secretary as the de facto governor of the city and the mayor as the executive head of the government working under the secretary.
What party rules Nanjing?

ANS: the CPC

QUES: Far from being a mere "stopgap" pope, to great excitement, John XXIII called for an ecumenical council fewer than ninety years after the First Vatican Council (Vatican I's predecessor, the Council of Trent, had been held in the 16th century). This decision was announced on 29 January 1959 at the Basilica of Saint Paul Outside the Walls. Cardinal Giovanni Battista Montini, who later became Pope Paul VI, remarked to Giulio Bevilacqua that "this holy old boy doesn't realise what a hornet's nest he's stirring up". From the Second Vatican Council came changes that reshaped the face of Catholicism: a comprehensively revised liturgy, a stronger emphasis on ecumenism, and a new approach to the world.
How many years had passed since Giulio Bevilacqua called for the First Vatican Council?

ANS: unanswerable

QUES: The conventional merit-system degree is currently not as common in open education as it is in campus universities, although some open universities do already offer conventional degrees such as the Open University in the United Kingdom. Presently, many of the major open education sources offer their own form of certificate. Due to the popularity of open education, these new kind of academic certificates are gaining more respect and equal "academic value" to traditional degrees. Many open universities are working to have the ability to offer students standardized testing and traditional degrees and credentials. A culture is beginning to form around distance learning for people who are looking to social connections enjoyed on traditional campuses. For example, students may create study groups, meetups and movements such as UnCollege.
 What do open education sources never offer?

ANS:
unanswerable