Physics holds 894 questions with answers, free to read and with no account needed. They are grouped into 1 category: Physics.
Attempt each question before revealing the answer, and keep a note of the ones you get wrong — those are the topics worth reading about properly. If an answer looks wrong, there is a link to report it on every question.
Answer: B. 25 cm
The normal human eye cannot focus sharply on objects closer than a specific limit. Ciliary muscles reach their maximum tension limit when viewing objects at this close range. Conventionally, this standard near point dist...
Answer: B. Electromagnetic waves
Transmitting antennas generate alternating electrical currents that create propagating electromagnetic fields. These oscillating fields travel outward through space as standard electromagnetic waves. Energy radiates cont...
Answer: A. Conduction band
The conduction band is the energy band that remains empty or partially filled. Electrons residing in this band possess enough energy to move freely through materials. This mobility allows the solid material to conduct el...
Answer: C. 100km
Fiber optic cables experience optical signal attenuation due to material absorption and Rayleigh scattering losses. To prevent signal degradation below detectable limits, engineers must regenerate or amplify the light pu...
Answer: C. Cadmium rods
Cadmium rods are commonly inserted into nuclear reactors to absorb excess neutrons. By capturing neutrons, they regulate and control the fission chain reaction rate. Inserting or withdrawing these control rods manages re...
Answer: B. S=Vit+1/2at2
Dimensional analysis requires that every added term in an equation share identical base dimensions. In the equation S equals initial velocity times time plus half acceleration times time squared. Each term in this kinema...
Answer: C. V02/√2R
Mean power dissipated by a resistor in an AC circuit is derived using RMS voltage and resistance values. Substituting root-mean-square voltage into the power formula yields the correct mathematical expression. Alternatin...
Answer: D. Converging source of electrons
Charged electrons respond strongly to electrostatic and magnetic Lorentz forces. Shaped electric and magnetic fields exert forces bending electron trajectories precisely. These fields act as converging lenses focusing el...
Answer: C. Inverter
An inverter is an electrical device that converts direct current power into alternating current power. Electronic switching circuits rapidly invert the DC polarity to create an oscillating AC waveform. Transformers are o...
Answer: D. kinetic energy
The average translational kinetic energy of an ideal gas molecule depends exclusively upon the absolute temperature. Temperature directly measures the average random kinetic energy possessed by the particles within a sub...
Answer: B. be doubled
Drift velocity of free electrons is directly proportional to the applied electric field inside conductors. Doubling the potential difference across the conductor doubles the electric field magnitude acting upon electrons...
Answer: A. black
Blue books absorb all light wavelengths except blue portion of spectrum. Monochromatic red light contains no blue wavelengths for the book to reflect. Absorbing all incoming illumination without reflection causes objects...
Answer: B. mg sinθ
The restoring force of a simple pendulum is the component of gravity acting tangent to the arc. Gravity pulls downward on the pendulum bob with a total force equal to the mass multiplied by gravity. Resolving this gravit...
Answer: A. Giga
The SI prefix giga represents a multiplier factor of ten to the ninth. This multiplier is significantly larger than mega or deca prefix values. Standard metric prefixes establish consistent scales for scientific data not...
Answer: B. Scanning electron microscope
A scanning electron microscope provides high-resolution imaging used for detailed structural analysis. By scanning a focused electron beam across a sample, it generates topographic surface images. This advanced microscop...
