Answer:
At 43.2°.
Step-by-step explanation:
To find the angle we need to use the following equation:
Where:
d: is the separation of the grating
m: is the order of the maximum
λ: is the wavelength
θ: is the angle
At the first-order maximum (m=1) at 20.0 degrees we have:
Now, to produce a second-order maximum (m=2) the angle must be:
Therefore, the diffraction grating will produce a second-order maximum for the light at 43.2°.
I hope it helps you!