Which of the following correctly describes the photoelectric effect?
AEmission of electrons from a metal when exposed to light of sufficient frequency
BEmission of electrons from a metal when exposed to light of any frequency
CAbsorption of light energy by electrons in a metal
DThe bending of light around obstacles
Correct Answer:
A. Emission of electrons from a metal when exposed to light of sufficient frequency
Explanation:
The photoelectric effect occurs when light of frequency greater than or equal to the threshold frequency strikes a metal surface, causing electron emission. It demonstrates the particle nature of light.
Which law of thermodynamics explains why heat cannot spontaneously flow from a colder body to a hotter body?
AFirst Law of Thermodynamics
BSecond Law of Thermodynamics
CThird Law of Thermodynamics
DZeroth Law of Thermodynamics
Correct Answer:
B. Second Law of Thermodynamics
Explanation:
The Second Law of Thermodynamics states that entropy of an isolated system increases or remains constant. Heat spontaneously flows from hot to cold, not vice versa, establishing the direction of processes.
