[a] ti} You are called as an expert witness in a trial. The defendant is accused of stealing information by reading a printed document that was pinned to a wall 50 m away. The defence says This is impossible but The prosecution has demon strated That the defendant has extremelyr good eyesight. What testimony 1would you glare?I You should assume the writing was similar in size to the printing on this exam paper. and your answer should be supported by physical arguments and a calculation. {ii} The prosecution now alleges that the defendant stole the information by taking a picture {from The same distance} with his mobile phone camera at high zoom. The lens of The camera has a diameter of 2 mm. Would your testimony change? Explain briefly. [b] You need to buy a diffraction grating for a spectrograph That rnust be able to resolve the sodium doublet {588.1195 mo and 589.592 nm}. The gratings in the catalogue are 2f\") mm wide and are blazed to work in rst order. Grating .21. has a groove spacing oftlf]I lines per mm and Grating B has a groove spacing oftlf]I lines per mm. Which grating should you choose? Justify your answer with a calculation