C28: Blue light of wavelength λ passes through a single slit of width aand forms a diffraction pattern on a screen. If the blue light is replaced by red light of wavelength 2λ,the original diffraction pattern is reproduced if the slit width is changed to

1. a/4.

2. a/2.

3. No change is necessary.

4. 2a.

5. 4a.

6. There is no width that can be used to reproduce the original pattern.