Adiffraction grating gives a second-order maximum at as angle of 31° for violet light (λ = 4.0 × 102 nm). if the diffraction grating is 1.0 cm in width, how many lines are on this diffraction grating? /3]

A47.2 g block of copper whose temperature is 480 k is placed in an insulating box with a 91.8 g block of lead whose temperature is 200 k. (a) what is the equilibrium temperature of the two-block system? (b) what is the change in the internal energy of the two-block system between the initial state and the equilibrium state? (c) what is the change in the entropy of the two-block system? the heat capacities of copper and lead are 386 j/kg·k and 128 j/kg·k, respectively.