Time: 20:00
Important one liner (Voltage and EMF)
- Electromotive force (EMF) is the work done per coulomb of charge, measured in volts, driving current through a circuit.
- Voltage between two points equals difference in electric potential energy per unit charge between those points.
- Internal resistance in a source reduces terminal voltage under load, causing a voltage drop proportional to current.
- Open-circuit voltage equals the EMF when no current flows, reflecting the ideal source potential.
- Back EMF in motors arises from motor rotation in magnetic field, opposing applied voltage and regulating speed.
- Faraday’s law states that induced EMF is proportional to the rate of change of magnetic flux linkage.
- Lenz’s law determines the direction of induced EMF opposing the change in magnetic flux that produced it.
- Contact potentials at junctions produce small thermoelectric EMFs dependent on material types and temperature differences.
- EMF in photovoltaic cells depends on light intensity, semiconductor properties, and temperature, influencing output voltage.
- Kirkhoff’s voltage law asserts that the algebraic sum of all EMFs and potential drops around any closed loop is zero.
- Capacitor charging involves voltage across plates increasing as charge accumulates, following Q = C · V relationship.
- Voltage dividers use series resistors to create adjustable voltages based on resistor ratios and supply EMF.
- Induced EMF in a coil due to self-inductance is proportional to the rate of change of current through the coil (L dI/dt).
- Motional EMF is generated when a conductor moves through a magnetic field at velocity v, giving ε = Bℓv.
- Chemical EMF in galvanic cells originates from redox reactions, creating potential differences determined by electrode materials.
- EMF drop in transmission lines is influenced by line resistance, reactance, load current, and conductor temperature.
- Peak, RMS, and average voltages characterize alternating voltages, with RMS value representing equivalent DC heating effect.
- Voltage regulation describes the ability of a power supply to maintain constant output voltage under varying load conditions.
- Spark gaps utilize high voltage breakdown of air to create discharge, demonstrating voltage threshold behavior.
- Corona discharge losses in high-voltage lines occur when electric field intensity exceeds air breakdown strength around conductors.
- Voltage harmonics in power systems arise from nonlinear loads, causing waveform distortion and power quality issues.
- EMF induced in a transformer primary depends on alternating current frequency, turns ratio, and core magnetic properties.
Keywords: Voltage quiz, EMF quiz, electromotive force questions, voltage definitions, Faraday's law quiz, Lenz's law quiz, internal resistance effects, open-circuit voltage, back EMF, transformer EMF, thermoelectric EMF, motional EMF, Kirchhoff's voltage law, capacitor voltage, voltage divider.
