发生干涉的两束光线一定满足
A. 两光线的波长相同
B. 两光线光矢量在同一方向上振动
C. 两光线的频率相同
D. 两光线的相位差恒定
来自不同光源的两束白光,例如两束手电筒光,射在同一区域内,是不能产生干涉花样的,这是由于( )
A. 白光是由许多不同波长的光构成的
B. 不同波长的光速是不相同的
C. 两光源发出不同强度的光
D. 两个光源是独立的,不是相干光源
Yu Lili wants to sign up for a volunteer organization. She is talking with Chen Fei about it. Listen to their conversation and fill in the blanks with the choices marked A to G.The Benefits Volunteering Work will Do for Yu Lili(1) ___________________________________;(2) ___________________________________;(3) ___________________________________.
A. no need to spend much time on her studies
B. improve her ability to communicate with people
C. leave campus to do volunteering work
D. help her get teamwork experience
E. help those people in need
F. add something to a nice-looking résumé
G. get some relaxation on Saturdays and Sundays