Physics is part of Physics and holds 894 questions with answers, free to read and with no account needed.
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: D. 0°
Mechanical work formula includes the cosine of the angle between vectors. The cosine of zero degrees evaluates to the maximum value of one. Therefore, parallel force and displacement vectors produce maximum work. Work is...
Answer: C. high energy photons
X-rays are packets of electromagnetic energy classified specifically as high-energy photons. Unlike electrons, photons possess no rest mass and travel at the speed of light. Wilhelm Röntgen discovered these mysterious ra...
Answer: A. torque
Work is calculated as force multiplied by displacement distance along its line. Torque is calculated as force multiplied by perpendicular lever arm distance. Both physical quantities share the exact same dimensional form...
Answer: C. γ-rays
X-rays and gamma rays are both forms of high energy electromagnetic radiation. They share identical fundamental wave and particle characteristics in physics. Their primary difference lies in their origin from atomic elec...
Answer: C. Systematic error
A zero error is a consistent, reproducible flaw inherent to a measuring instrument's calibration, categorizing it as a systematic error. Because the offset remains constant across repeated trials, it shifts every recorde...
Answer: A. insulator
Insulators possess very wide forbidden energy gaps between valence and conduction bands. Thermal energy at room temperature cannot excite electrons across this wide gap. This absence of free charge carriers prevents elec...
Answer: D. The wavelengths of X-rays are of the same order of magnitude as the separation between atoms in a crystal
Diffraction requires spatial periodicity comparable to the wavelength of the incident wave. X-ray wavelengths measure around one angstrom, matching atomic plane separations inside crystals. Ordinary ruled diffraction gra...
Answer: B. Greek
Ancient Greek philosophers were among the first to systematically investigate natural phenomena without relying solely on mythology. Thinkers like Aristotle and Archimedes laid foundational concepts in mechanics, optics,...
Answer: B. to decrease current
Adding a resistor in series increases the total equivalent resistance of the electrical circuit. Ohm law states that current equals voltage divided by total circuit resistance. A higher total resistance directly results...
Answer: B. Increases
Higher external pressure exerts a greater downward force on liquid molecules attempting to escape. Molecules require additional thermal kinetic energy to overcome this increased external atmospheric barrier. This extra e...
Answer: B. always negative
Frictional force always acts in the direction opposing object movement. Displacement and opposing friction vectors form a one hundred eighty degree angle. The cosine of one hundred eighty degrees is negative one, making...
Answer: B. due to air resistance
Atmospheric friction generates unpredictable aerodynamic drag forces that disrupt the planned trajectory of ballistic missiles. Air resistance creates complex turbulence patterns around the missile body during high speed...
Answer: D. γ-rays
X-rays and gamma rays are both located at the extreme high-frequency end of the spectrum. Both radiation types consist of high-energy photons traveling at the speed of light. Their electromagnetic wave nature allows them...
Answer: C. Solid only
Young modulus specifically measures elastic stiffness and deformation in solid structural materials. Gases and liquids lack fixed shapes and do not support tensile or compressive elastic stiffness in the same manner. Flu...
Answer: D. tungsten
Tungsten possesses an extremely high melting point exceeding three thousand four hundred degrees Celsius. Its exceptionally low vapor pressure at high temperatures prevents rapid evaporation of the filament wire inside t...
