Physics Essentials: 17 MCQs with answers

Non-Destructive Testing

NDT is the standard acronym for Non-Destructive Testing, a method to inspect materials without causing damage.

Blackbody radiation

Classical physics could not explain blackbody radiation, leading to Planck's quantum hypothesis.

Max Planck

Max Planck proposed that energy is emitted in discrete quanta, forming the basis of quantum theory.

Light

The photoelectric effect is the emission of electrons when light (electromagnetic radiation) strikes a material.

Wave

De Broglie proposed that particles like electrons exhibit wave-like properties, with a wavelength given by h/p.

ψ (psi)

The wave function is conventionally represented by the Greek letter psi (ψ).

False

The uncertainty principle is a fundamental property of quantum systems and applies to all particles, but its effects are negligible for macroscopic objects.

Particle nature of X-rays

The Compton effect shows that X-rays behave as particles (photons) when scattering off electrons.

Wave nature of electrons

Davisson and Germer observed electron diffraction, providing experimental proof of de Broglie's wave hypothesis.

Position and momentum of a particle

The uncertainty principle sets a fundamental limit on the precision of measuring position and momentum together.

It must be continuous and single-valued

A valid wave function must be continuous, single-valued, and finite to be physically meaningful.

Max Planck

Planck's law describes the spectral energy distribution of blackbody radiation.

Particles exhibit both wave and particle properties

Wave-particle duality is the concept that every quantum entity exhibits both wave and particle characteristics.

Momentum

The de Broglie wavelength λ = h/p, so it is inversely proportional to momentum p.

Detect internal flaws in materials

Ultrasonic testing uses high-frequency sound waves to detect internal defects without damaging the material.

Photons

Einstein proposed that light consists of discrete packets of energy called photons to explain the photoelectric effect.

False

The probability density is given by |ψ|², not ψ itself. The wave function is a complex quantity whose modulus squared gives the probability.