Sodium's emission lines at 589.0 nm and 589.6 nm pass through a diffraction grating and form two m = +1 maxima on a viewing screen. Would the spacing between the two lines increase, decrease, or remain unchanged if the grating is exchanged for one having fewer lines per millimeter, or for one with twice the total number of lines? What if the intensity of the light is doubled, or the maxima are viewed in second order? HINT (a) The grating is exchanged for one having fewer lines per millimeter. The spacing increases. The spacing decreases. The spacing remains unchanged. (b) The grating is exchanged for one with twice the total number of lines. (The number of lines per millimeter is the same.) The spacing increases. The spacing decreases. The spacing remains unchanged. (c) The intensity of the light is doubled. The spacing increases. The spacing decreases. The spacing remains unchanged. (d) The maxima are viewed in second order. The spacing increases. The spacing decreases. The spacing remains unchanged.