Physics 346 FY Quiz

Capacitors and Their Configurations

• Two capacitors with capacitances C₁ µF and C₂ µF have a combined capacitance of 20 µF when connected in parallel.
• When connected in series, their total capacitance is 4.8 µF.
• The ratio of capacitances C₁ and C₂ can be derived using the formulas for series and parallel combinations.

Forces Between Current-Carrying Conductors

• The force between two parallel, straight current-carrying conductors can be attractive or repulsive.
• The force is attractive when currents flow in the same direction and repulsive when they flow in opposite directions.
• This behavior is due to the magnetic fields generated by the currents interacting with each other.

Resonant Circuits

• A resonant circuit, commonly called an L-C-R circuit, has specific conditions for resonance: impedance must be minimum, and the inductive reactance must equal capacitive reactance.
• The expression for the resonant frequency is given by: ( f = \frac{1}{2\pi\sqrt{LC}} ), where L is inductance and C is capacitance.

Einstein's Photoelectric Equation

• The equation describes the photoelectric effect, showing that the energy of photons (E = hf) exceeds the work function (φ) of the metal.
• For a metal plate with a work function of 0.5 eV, photons with energies of 1 eV and 2.5 eV yield maximum kinetic energies for emitted electrons represented as ( k₁ ) and ( k₂ ).
• Ratios ( k₁/k₂ ) and ( v₁/v₂ ) can be calculated based on the energy of the incoming photons minus the work function.

Magnetic Torque on a Current Loop

• The formula for torque acting on a current-carrying loop in a uniform magnetic field can be established from the concept of magnetic moment.
• Magnetic dipole moment is defined as the product of the current flowing through the loop and the area vector of the loop.

Definitions and Concepts

• Displacement Current: Introduced by Maxwell, it accounts for changing electric fields in situations where conduction current may not flow, influencing electromagnetic phenomena.
• Microwaves: A type of electromagnetic radiation, classified based on wavelength and frequency, used in applications like microwave ovens and communication technologies.
• Polarization Angle: Refers to the angle at which the electric field vector of a light wave oscillates relative to its propagation direction.
• p-n Junction Diode: Can be forward or reverse biased based on the connection of the p-type and n-type materials; used in various electronic applications including rectification.
• Henry: A unit of self-inductance when a change of current of one ampere induces an electromotive force of one volt.
• Current Density: Defined as current per unit area of cross-section, represented in units of A/m².

Additional Calculations

• Equations relating to the drift speed and potential difference can be derived for conductors.
• The ratio of de Broglie wavelengths for proton and α-particles, kinetic energy relationships, and definitions of mass defect and binding energy are critical in nuclear physics.
• Current flowing through a circuit, given as 5 mA, can be utilized to find the resistance using Ohm's law, based on applied voltage drops in the circuit.