What is the approximate dimensionless ratio k e² / (G mₑ mₚ) comparing the electric force to the gravitational force between an electron and a proton?

Why is charge quantization usually ignored for macroscopic charges (such as a few microcoulombs)?

The potential energy U of an electric dipole p placed in a uniform electric field E, taking U = 0 when the dipole is perpendicular to the field, is:

What is the electrostatic energy density uE in a region with electric field E in vacuum, where ε₀ is the permittivity of free space?

What is the electric field E just outside the surface of a charged conductor with surface charge density σ and outward normal unit vector n̂?

The average drift velocity vd of electrons in a conductor under electric field E, in terms of electron charge (−e), electron mass m, and relaxation time τ, is:

Ohm’s law in vector form is j = σE. If ρ is resistivity, the equivalent relation is:

The resistivity of semiconductors decreases with temperature mainly because:

According to the Biot-Savart law, the magnetic field dB due to an infinitesimal current element I dl is zero at point P when:

For a circular current loop of magnetic moment m and radius R carrying current I, the approximate magnetic field B at a large axial distance x (x >> R) is:

A magnetic force F = q (v × B) does not work on a charged particle. Therefore it does not change which property?

Gauss’s Law for magnetism (closed surface integral of B · dS = 0) expresses which property?

A material is diamagnetic if its magnetic susceptibility χ lies in the range:

A defining property of magnetic field lines, unlike electrostatic lines, is that they:

A straight conductor of length l moves with velocity v perpendicular to a magnetic field B. The induced EMF ε is:

What is the magnetic potential energy U stored in a coil of self-inductance L when a steady current I flows through it?

A coil of N turns and area A rotates with angular speed ω in a magnetic field B. The peak EMF ε₀ generated is:

In a pure inductor with voltage v = vm sin(ωt), the current amplitude is im = vm/ Xₗ. Which describes the phase and the instantaneous current?

In a series RLC circuit, the current is maximum at resonant frequency ω₀. What is the relation between Xₗ and Xc and the impedance Z?

A resistor connected to AC source v = vm sin(ωt) dissipates instantaneous power p = im² R sin²(ωt). What is the average power over one cycle in terms of rms current I and resistance R?

In the Ampere-Maxwell law, the displacement current id is defined in terms of electric flux ΦE as:

An electromagnetic wave travels in free space with electric field Ex = E₀ sin(kz − ωt). If propagation is along +z, what is the direction of the magnetic field component By?

The speed v of an EM wave in a material with permeability μ and permittivity ε is:

In Young’s double-slit experiment, if the path difference at point P is (n + 1/2)λ, what occurs?

Using Huygens’ principle for refraction, which relationship holds between angle of incidence i, angle of refraction r, speeds v₁ and v₂, and wavelengths λ₁ and λ₂?

Unpolarised light of intensity Iipasses polaroid P1 and then P2, giving final intensity Ii/4 What is the angle θ between their pass axes?

An electron of mass 9.11 × 10⁻³¹ kg moves at 5.4 × 10⁶ m/s. Using h = 6.63 × 10⁻³⁴ J·s, what is its de Broglie wavelength?

Einstein’s photoelectric equation gives Kmax = hν − φ₀. If ν = ν₀ (threshold frequency), what is true?

Which observation of the photoelectric effect contradicts classical wave theory?

For thin lenses in contact, total power P = P₁ + P₂ + ... A convex lens (P₁ = +2.5 D) and concave lens (P₂ = −4.0 D) are in contact. What is the effective focal length?

An object is at u = −100 cm from a spherical surface (n₂ = 1.5) with radius R = +20 cm. Light goes from air (n₁ = 1) to glass. Using formula n₂/v − n₁/u = (n₂ − n₁)/R, where is the image?

Critical angle ic for TIR satisfies n₁₂ = 1 / sin ic. For diamond (n = 2.42), the critical angle is:

The total energy of the electron in a hydrogen atom is given by En = -13.6 eV / n². What is the ratio of the energy required to excite a hydrogen atom from its ground state (n = 1) to its second excited state (n = 3) compared to the energy required to excite it to its first excited state (n = 2)?

Rutherford's nuclear model of the atom was a major step forward, but it failed to explain why atoms emit light of only discrete wavelengths. According to classical electromagnetic theory, what erroneous type of spectrum would Rutherford's model predict due to the revolving electrons?

In the Geiger-Marsden experiment, a 7.7 MeV alpha-particle is used to determine the distance of closest approach (d) to a gold nucleus (Z = 79). If the experiment were repeated using a different target foil having an atomic number of Z = 40, and assuming the same alpha-particle energy, how would the new distance of closest approach (d') relate to the original distance (d)?

Which of the following statements concerning the stability of atomic models, based on classical physics, is correct?

The binding energy per nucleon (Ebn) curve shows that for nucleons with mass numbers in the range 30 < A < 170, Ebn is practically constant. This constancy is a direct consequence of which property of the nuclear force?

Given that the atomic mass unit 1 u = 1.6605 × 10⁻²⁷ kg, calculate the energy equivalent in Joules (J) released if 1 u of mass is completely converted into energy (where c ≈ 3.00 × 10⁸ m s⁻¹)?

Which of the following nuclides are classified as isotones?

In the context of the nuclear force potential energy curve, what is the approximate separation distance r₀ at which the potential energy between two nucleons reaches a minimum?

The conductivity (σ) of an intrinsic semiconductor depends on temperature. At T = 0 K, how does an intrinsic semiconductor behave, and what is the physical reason for this?

In Silicon, the energy gap Eg is 1.1 eV. To create an n-type semiconductor, a pentavalent impurity like Arsenic (As) is added. What is the approximate ionization energy required to free the extra conduction electron donated by the As atom, relative to the intrinsic band gap?

When operating a p-n junction diode, the dynamic resistance (rd) is defined as the ratio of a small change in voltage (ΔV) to a small change in current (ΔI). During which bias condition is this dynamic resistance typically lowest, and what is its magnitude?

The heat produced in a resistor is directly proportional to: