In a double-slit interference experiment, which of the following actions (perhaps more than one) would cause the fringe spacing to increase? (a) Increasing the wavelength of the light. (b) Increasing the slit spacing. (c) Increasing the distance to the viewing screen. (d) Submerging the entire experiment in water

The correct option is a , c

Explanation:

Generally the  fringe spacing is mathematically defined as

Where y is the fringe spacing

           m is the order of the fringe

            is the wavelength

           D is the distance between the slit and the screen

           d is the distance between the slit

Now in order to increase the fringe spacing can do the following

The following action would increase the fringe spacing because the from the question these parameters are directly proportional to the fringe spacing

you would expect a sound wave to speed up. - b)