The wave nature

The uncertainty principle defines the limits of how much it is possible to know about a particle.

However, the phenomenon described as wave-particle duality is not real. It is the result of our failure to understand the real impact of the uncertainty principle.

• True

• False

The tendency of some particles to act like matter in public and like waves of energy when no one's looking may be a problem in the way physicists study particles, not the way particles behave.

• True - The methods used by physicists are to blame

• False - Particles really have dual nature

Is it possible to rephrase the uncertainty principle as follow

"we can't see all the characteristics of a particle at one time, every time we look at a quantum particle we must be seeing only a subset of the things about it we would like to see.

If the list of characteristics we can see changes more than we realize,we may see particles doing things that are impossible simply because we haven't realized the information we see about it has changed from one observation to the next."

• Yes

• No

The Heisenberg’s uncertainty principle states that there is a fundamental limit to the accuracy with which the position and momentum of a particle can simultaneously be known or jointly measured. Position and momentum are called complementary variables and there are other complementary pair of variable that exists for any quantum particle.

• True

• False

The Heisenberg's Indeterminacy Equation is given by ΔpΔx ≥ ℏ/2 (where ℏ=h/2π). The limit of accuracy ℏ/2 is also called as the constraining constant which is an experimentally determined constant. With more accurate experimental procedures this value is subject to change.

• True

• False

Solar sails (also called light sails or photon sails) are a method of spacecraft propulsion. Solar sails can achieve upto 10% the speed of light, which is ~30000 km/s. The conservation of what fundamental physics principle is behind the technology of solar sails?

• charge

• mass

• momentum

• angular momentum

Answer explanation

Momentum is conserved in quantum mechanics, just as it is in relativity and classical physics.

Large objects can move with great momentum. Why then is it difficult to see their wave-like nature?

• Their wavelength is equal to the object’s size.

• Their wavelength is very small compared to the object’s size.

• Their wavelength is very large compared to the object’s size.

• Their frequency is very small compared to the object’s size.

Light has no mass so it also has no energy according to Einstein.

• True

• False

Answer explanation

The equation E = mc² is actually a special case of the more general equation

E² = p²c² + m²c⁴

In the above equation, E is the total energy of the particle, p is the momentum of the particle (which is related to its motion), c is the speed of light, and m is the mass of the particle.

Therefore, if an object with no mass is to physically exist, it can never be at rest. Such is the case with light.

To calculate the frequency of an electromagnetic wave, you need to know the speed of the wave and its

• wavelength.

• intensity.

• refraction.

• amplitude.

Which of the following experiment suggested the wave nature of electrons?

• the emission of electrons when electromagnetic radiation, such as light, hits a material.

• diffraction of electrons by the surface of Nickel metal

• radioactive decay in which a fast energetic electron or positron is emitted from an atomic nucleus,

• streams of electrons observed if an evacuated glass tube is equipped with two electrodes and a high voltage is applied