Which one of the following actions would make the maxima in the interference pattern from a grating move closer together?
Decreasing the frequency of the laser.
Increasing the frequency of the laser.
Increasing the number of lines per length.
Increasing the wavelength of the laser.
Increasing the number of lines per length.
To determine which action would make the maxima in the interference pattern from a grating move closer together, we need to understand the factors that affect the spacing between the maxima.
The interference pattern from a grating is created by the interference of light waves passing through multiple slits or lines in the grating. The spacing between the maxima is determined by the wavelength of the light, the distance between the slits or lines on the grating, and the angle of observation.
Now let's analyze the four given actions:
1. Decreasing the frequency of the laser: The frequency of light is directly proportional to its wavelength (speed of light = frequency x wavelength). Decreasing the frequency would result in an increase in the wavelength of the light. Since the spacing of maxima is directly proportional to the wavelength, decreasing the frequency would make the maxima move further apart, not closer together.
2. Increasing the frequency of the laser: As explained earlier, the frequency of light is directly proportional to its wavelength. Increasing the frequency would result in a decrease in the wavelength of the light. Since the spacing of maxima is directly proportional to the wavelength, increasing the frequency would make the maxima move closer together.
3. Increasing the number of lines per length: This action would increase the density of the grating, but it would not directly affect the spacing between the maxima. The distance between the slits or lines on the grating plays a role in determining the position and intensity of the maxima, but not the spacing between them.
4. Increasing the wavelength of the laser: Increasing the wavelength of the laser would directly increase the spacing between the maxima. Therefore, this action would make the maxima move further apart, not closer together.
Therefore, the correct answer is: Increasing the frequency of the laser.