phy problem

if normal white light......
single slit shall be used in front of the doulbe slit to have coherent

for different wavelength,
the width(maximum's postion) is different,
you may imagine many single wavelength's patterns superpositioned together .....
--> whight light at the central maximum, changing color aside

2007-04-19 15:49:14 補充：
oh, it's MC question.......I choose E

only 2 light lines exist