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A particle is moving three times as fast as an electron. The ratio of the de Broglie wavelength of the particle to that of electron is 1.813×10-4. Calculate the particle's mass and indentify the particle.

                                                                                                                   2mark

Explanation:

de Broglie wavelength of a moving particle, having mass m and velocity v:

λ=h/p=h/mv

Mass, m=h/λv                                                                                     1/2mark

For an electron, mass me=h/λeve

Now, we have v/ve=3 and λ/λe=1.813×10-4                                       1/2mark

Then, mass of the particle, m=me  λe/λve/v                                      1/2mark

m=9.11×10-31kg×1/3×1/1.813×10-4

m=1×1.675×10-27kg.

Thus, the particle, with this mass could be a proton or a neutron.                       1/2mark

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