An 18-mm-wide diffraction grating has rulings of 710 lines per millimeter. monochromatic light of wavelength 506 nm wavelength is incident normally on the grating. what is the largest angle from the centerline at which an intensity maximum is formed?

W= 18*10^-3m 
N= 18*710 ( because you have 710 slits per mm ) = 12780 
lambda = 506*10^-9 

The first step is to workout d. 
d = w/N 
d =18*10^-3m/12780 
d =1.41*10^-6m 

The second step is to work out the maximum number of m. 
Since sin (theta) = less than 1, then m*lambda/d = less then 1,
therefore m= less than d/lambda 
( I know thats confusing but trust me ) 
so m is less than 1.41*10^-6m/506*10^-9 
= 2.7 
Therefore use m = 2 

Lastly put it all into the formula
dsin (theta) = m*lambda so:
theta = sin^-1(m*lambda/d) 
theta = sin^-1(2*506*10^-9/1.41*10^-6m) 
theta = 45.95 degrees or 46 degrees

stands for electromotive force and it is measured in volts. despite its name, it is not actually the force in the sense of being a "pushing" or "pulling" (not measured in newtons).an equation that relates emf,  ℰ,  to a battery's terminal voltage, v, current, i, and internal resistance, r, is    ℰ = v + irin this case, the emf can be interpreted as a voltage—a difference in electric potential.i would not say that it would be considered an energy. if emf can be defined as the energy/work per a unit charge from a battery or other electric source, then it is not strictly energy.