21. The branch of physics that deals with the behavior of light is called:
a) Thermodynamics
b) Optics
c) Acoustics
d) Electromagnetism
Answer: b) Optics
22. The speed of light in a vacuum is approximately:
a) 300,000 m/s
b) 3 x 10⁸ m/s
c) 9.8 m/s²
d) 10 m/s
Answer: b) 3 x 10⁸ m/s
23. The phenomenon in which a wave encounters an obstacle and bends around it is called:
a) Refraction
b) Reflection
c) Diffraction
d) Dispersion
Answer: c) Diffraction
24. The process of converting a gas into a liquid by cooling is called:
a) Evaporation
b) Sublimation
c) Condensation
d) Melting
Answer: c) Condensation
25. Which law states that the pressure of a gas is inversely proportional to its volume at constant temperature?
a) Boyle’s law
b) Archimedes’ principle
c) Pascal’s law
d) Newton’s law of cooling
Answer: a) Boyle’s law
