1011 past contests
Topic 59 · Power dissipated by a resistor: from voltage and resistance, and from power and resistance
Topic 25 · Riddle: the quark, named from finnegans wake
Topic 20 · Carbon-14 forms from nitrogen-14, not carbon-12, via cosmic-ray bombardment (true/false)
Topic 2 · Gravitational work around a closed path is zero, not proportional to path length (true/false)
Topic 20 · Carbon-14 beta decay produces nitrogen-14 (true/false)
Topic 27 · A carnot refrigerator has the maximum coefficient of performance between two temperatures (true/false)
Topic 9 · Ciliary muscles relax (not contract) to focus on distant objects (true/false)
Topic 36 · Work done by friction is path-dependent (true/false)
Topic 27 · Otto-cycle thermal efficiency increases, not decreases, with compression ratio (true/false)
Topic 5 · Work done by an electrostatic field is path-independent (true/false)
Topic 27 · The stirling engine achieves the maximum thermal efficiency of any heat engine between two temperatures (true/false)
Topic 46 · Problem of the day: choosing lens type and focal length for a long-sighted (hyperopic) reader
Topic 40 · Op-amp inverting differentiator: input resistor replaced by a capacitor
Topic 40 · Op-amp logarithmic amplifier: feedback resistor replaced by a diode
Topic 40 · Op-amp inverting integrator: feedback resistor replaced by a capacitor
Topic 27 · Thermal efficiency of a heat engine from work done and heat rejected
Topic 27 · Thermal efficiency of a heat engine from heat absorbed and heat rejected
Topic 27 · Work done by a heat engine from its efficiency and the heat rejected
Topic 20 · The neutrino as a fundamental particle among deuteron/alpha particle/neutrino
Topic 25 · The antineutrino as a fundamental particle among antineutron/antineutrino/proton