Young-fringe positions scale through a checked path-source wavelength. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Short wavelength lands at two metres

The path source first checks wavelength 1 m. With first order, screen distance six metres, and slit spacing three metres, the fringe position is 2 m.

y=1163=2y=\frac{1\cdot1\cdot6}{3}=2
Young wavelength source rowThe path source and Young fringe check are both present.path Apath Bfringe y

Double wavelength doubles the fringe position

The path source first checks wavelength 2 m. With first order, screen distance six metres, and slit spacing three metres, the fringe position is 4 m.

y=1263=4y=\frac{1\cdot2\cdot6}{3}=4
Young wavelength source rowThe path source and Young fringe check are both present.path Apath Bfringe y

Triple wavelength triples the fringe position

The path source first checks wavelength 3 m. With first order, screen distance six metres, and slit spacing three metres, the fringe position is 6 m.

y=1363=6y=\frac{1\cdot3\cdot6}{3}=6
Young wavelength source rowThe path source and Young fringe check are both present.path Apath Bfringe y