由六节干电池串联组成的电池组，对一电阻供电，电路中的电流为2A，在10 s内电源做功为180 J，则电源的电动势为多少？从计算结果中你能得到什么？
解：电源做的功就是非静电力搬运电荷做的功，在10 s内共搬运的总电荷量为：
q=It=2×10 C=20 C
再根据W=qE，式中的E为电源电动势，则
每一节干电池的电动势为1.5 V，9V相当于把6个1.5 V相加，也就是说，串联电池组的总电动势等于各电动势之和
In this section you will find after each of the passages a number of questions or unfinished statements about the passage, each with 4 (A, B, C and D) choices to complete the statement. You must choose the one which you think fits best. Then blacken the corresponding letter as required on your Machine-scoring ANSWER SHEET. The time for this section is 70 minutes.
| Social control refers to social processes, planned or unplanned, by which people are taught, persuaded, or forced to conform to norms. In every society, some punishments or negative sanctions are established for deviant behavior. Without deviant behavior there would not be need for social control and without social control there would not be a way of recognizing the boundary between the acceptable and the unacceptable. Social control may be either formal or informal. Informal mechanisms include expressions of disapproval by significant others and withholding of positive rewards for disapproved behavior. Most people internalize norms in the course of socialization. This is any group’s most powerful protection against deviance, in that the individual’s own conscience operates as an agent of social control. When informal sanctions fail, formal agents of social control may be called upon. In contemporary society, such formal agents and agencies include psychiatry and other mental health professions; mental hospitals; police and courts of law; prisons; and social welfare agencies. All these formal agents function to limit, correct, and control violation of norms. Conflict theorists would also point out that social control agents and systems tend, in any society, to serve the interests of powerful groups and to enforce the norms most beneficial to those who make the rules and who, therefore, define unacceptable behavior. Social control, whether formal or informal, has a dual function. First, it punishes the wrongdoer and reaffirms the boundaries of acceptable behavior. Second, and less recognized, it regulates the manner in which deviants are treated. |
In the third paragraph, "a dual function" refers to______.
A．formal and informal
B．rewards and penalties
C．approval and disapproval
D．clarification and regulation