The formula is eight times D, minus B, time C.

公式是8*D-B*C。

The path difference is equal to the width of the slit, D, times the sine of the angle between the point on the screen and a line straight from the slit to the screen.

路径差等于狭缝的宽度 D 乘以屏幕上的点与从狭缝到屏幕的直线之间的夹角的正弦值。