Correct Answer - Option 2 : β - particle
Concept:
Matter waves:
The light is a wave having particle nature. In a similar way, we say that the matter moving at a certain speed is having wave-like characteristics.
The wavelength of such wave is called de Broglie wavelength.
- de Broglie wavelength associated with the particle is given as
\( \lambda = \frac{h}{p} = \frac{h}{mv}\) -----(1)
h is Planck's constant, p is momentum.
α particle:
-
Alpha rays are positively charged particles.
- An α particle is essentially a He nucleus consisting of two protons and two neutrons.
- Two protons correspond to 2 units of positive charge on an α particle.
- Two protons and two neutrons correspond to 4 units of mass of an α particle.
- The symbol for an α particle is 4He2.
β particle:
- β particles are high-speed electron or its positive counter part positron emitted by the radioactive decay.
- There are two types of β particle, β− (electron) and β+ (positron) having mass same as an electron.
Explanation:
From de Broglie equation we have
\( \lambda = \frac{h}{p} = \frac{h}{mv}\)
\(\implies \lambda \propto \frac{1}{m}\)
h is constant and it is given velocity v is also constant.
So, the particle with minimum mass will have a maximum wavelength.
β particle has mass same as an electron which is having a much lower mass than proton or neutron.
So, the correct option is β - particle
