Referring to Chapter 38 this question has three sections Eac

Referring to Chapter 38, this question has three sections. Each section is multiple choice, please select one answer per section.

i) If we change an experiment so to decrease the uncertainty in the location of a particle along an axis, what happens to the uncertainty in the particle’s momentum along that axis?

increases

decreases

remains the same

ii) Under what energy circumstances does an electron tunnel through a potential barrier? Explain selected.

when the kinetic energy is greater than the potential energy

when the potential energy is greater than the total energy

when the potential energy is less than the total energy

iii) How does an electron’s de Broglie wavelength after tunneling compare with that before tunneling (when the potential energy is the same before and after, as in this section)?

The wavelength is the same after tunneling.

The wavelength is greater after tunneling.

The wavelength is less after tunneling.

Solution

1) If we design the experiment to decrease the uncertainity in position then as per Heisenberg\'s uncertainity principle, the uncertainity in momentum increases;

Heisenberg\'s Uncertainity principle: The product of uncertainities in position and momentum is always constant.

2) The phenomena of tunnelling can be observed when the potential of the barrier is greater than the total energy of the particle. Ans (b)

When the energy is greater than potential then the wave just passes through it. Tunneling is the quantum phenomena in which the wave propagates through barrier even it doesn\'t have sufficient energy.

3) The wavelength remains same before and after tunnelling through the potential as per energy conservation principle.