You short-circuit a 9 volt battery by connecting a short wire from one end of the battery to the other end. if the current in the short circuit is measured to be 18 amperes, what is the internal resistance of the battery?

The two most prominent wavelengths in the light emitted by a hydrogen discharge lamp are 656(red) and 486 (blue). light from a hydrogen lamp illuminates a diffraction grating with 500 lines per mm, and the light is observed on a screen 1.50 behind the grating. what is the distance between the first-order red and blue fringes?