<P> Like a wave, cathode rays travel in straight lines, and produce a shadow when obstructed by objects . Ernest Rutherford demonstrated that rays could pass through thin metal foils, behavior expected of a particle . These conflicting properties caused disruptions when trying to classify it as a wave or particle . Crookes insisted it was a particle, while Hertz maintained it was a wave . The debate was resolved when an electric field was used to deflect the rays by J.J. Thomson . This was evidence that the beams were composed of particles because scientists knew it was impossible to deflect electromagnetic waves with an electric field . These can also create mechanical effects, fluorescence, etc . </P> <P> Louis de Broglie later (1924) showed in his doctoral dissertation that electrons are in fact much like photons in the respect that they act both as waves and as particles in a dual manner as Einstein had shown earlier for light . The wave - like behaviour of cathode rays was later directly demonstrated using a crystal lattice by Davisson and Germer in 1927 . </P>

Why are electrons in a cathode ray tube deflected by magnetic and electric fields