You measure the emission spectrum of an atom that you suspect to be hydrogen. You have noabsolute calibration of the wavelength, but theratiosof the first 3 wavelengths in the seriesthat you measure are 1 : 0.741 : 0.661. Which series is this (e. g. Lyman, Balmer, Paschen, Brackett...)

Asimple speed reducer is composed of 2 spur gears. the pinion gear has a pitch diameter of 0.75" and 36 teeth while the driven gear has a pitch diameter of 4.0" and 192 teeth. a)-what is the diametral pitch of each gear? b)-if an electric motor rotating ccw at 3000 rpm is coupled to the pinion, what is the rotational speed of the driven gear? c)-if the torque delivered to the pinion is 1 n-m, what is the torque on the driven gear? d)-what is the power transmitted by the gear train?