1011 past contests
Topic 46 · Focal length of a converging lens from an object distance and a threefold virtual, upright image distance
Topic 41 · Orbit radius of a charged particle in a magnetic field from charge/mass ratio, speed and b
Topic 41 · Charge/mass ratio of a particle in a magnetic field from speed, orbit radius and b
Topic 46 · Effective focal length of two identical thin lenses in contact
Topic 46 · Effective focal length of two thin lenses in contact (opposite-sign focal lengths)
Topic 46 · Effective focal length of two thin lenses in contact (a converging and diverging lens)
Topic 16 · Mass flow rate of a fluid from density, pipe area, and flow speed
Topic 64 · Frequency of a transverse wave from its angular frequency in the wave equation
Topic 26 · Shortest (cutoff) x-ray wavelength from the accelerating voltage of an x-ray tube
Topic 20 · Riddle: mass defect, the nucleon-mass/nuclear-mass difference
Topic 30 · Radiation occurs through matter too, not only vacuum (true/false)
Topic 20 · Same total nucleon count defines isobars, not isotopes (true/false)
Topic 20 · Isotones share the same neutron number (true/false)
Topic 20 · Same nucleon count means same mass number, by definition (true/false)
Topic 30 · Convection occurs in gases as well as liquids, not liquids alone (true/false)
Topic 30 · Gases can transfer heat by both radiation and convection (true/false)
Topic 48 · Problem of the day: minimum-deviation prism angle and refractive index from a given deviation
Topic 10 · Work done by an ideal gas during isobaric expansion
Topic 34 · Coefficient of restitution from an object's drop and rebound heights