Modern Physics is a crucial subject in the curriculum of Indian students, especially for those preparing for school exams and competitive tests. Understanding the principles of Modern Physics not only enhances conceptual clarity but also plays a significant role in scoring better. Practicing MCQs and objective questions helps students identify important questions and solidify their knowledge, making exam preparation more effective.
What You Will Practise Here
Photoelectric Effect and its applications
Quantum Theory and its implications
Nuclear Physics: Fission and Fusion processes
Relativity: Concepts of time dilation and length contraction
Wave-Particle Duality and its significance
Atomic Models: Bohr's model and Quantum Mechanical model
Important formulas related to energy, momentum, and mass-energy equivalence
Exam Relevance
Modern Physics is a significant part of the syllabus for CBSE, State Boards, NEET, and JEE. Questions from this topic often appear in various formats, including multiple-choice questions, numerical problems, and theoretical explanations. Common question patterns include conceptual applications of theories, derivations of formulas, and problem-solving based on real-world scenarios. Mastering this subject can greatly enhance your performance in these competitive exams.
Common Mistakes Students Make
Confusing the concepts of classical and modern physics
Misunderstanding the implications of the photoelectric effect
Overlooking the significance of units and dimensions in calculations
Neglecting to apply the principles of relativity correctly in problems
Failing to connect theoretical concepts with practical applications
FAQs
Question: What are some important Modern Physics MCQ questions I should focus on? Answer: Focus on topics like the photoelectric effect, nuclear reactions, and the principles of relativity, as these are frequently tested in exams.
Question: How can I improve my understanding of Modern Physics concepts? Answer: Regular practice of objective questions and solving previous years' papers can significantly enhance your understanding and retention of key concepts.
Start your journey towards mastering Modern Physics today! Solve practice MCQs to test your understanding and boost your confidence for upcoming exams. Remember, consistent practice is the key to success!
Q. If a metal has a work function of 2 eV, what is the minimum wavelength of light required to cause the photoelectric effect?
A.
620 nm
B.
310 nm
C.
1240 nm
D.
500 nm
Solution
Using the equation λ = hc/E, where E = 2 eV = 2 * 1.6 x 10^-19 J, we find the minimum wavelength λ = (6.63 x 10^-34 J·s * 3 x 10^8 m/s) / (2 * 1.6 x 10^-19 J) = 310 nm.
Q. If a metal has a work function of 2 eV, what is the threshold wavelength for the photoelectric effect?
A.
620 nm
B.
400 nm
C.
500 nm
D.
300 nm
Solution
The threshold wavelength can be calculated using the equation λ = hc/W. Substituting h = 4.14 x 10^-15 eV·s, c = 3 x 10^8 m/s, and W = 2 eV gives λ = 620 nm.
Q. If a metal has a work function of 4 eV, what is the minimum wavelength of light required to cause the photoelectric effect?
A.
310 nm
B.
620 nm
C.
1240 nm
D.
2480 nm
Solution
The minimum wavelength can be calculated using the equation λ = hc/W. Substituting h = 4.14 x 10^-15 eV·s, c = 3 x 10^8 m/s, and W = 4 eV gives λ = 310 nm.
Q. If the frequency of incident light is doubled, what happens to the kinetic energy of the emitted electrons?
A.
It remains the same
B.
It doubles
C.
It quadruples
D.
It decreases
Solution
The kinetic energy of the emitted electrons is given by KE = hf - φ. If the frequency is doubled, the kinetic energy increases as it is directly proportional to frequency.
Q. If the intensity of light is doubled while keeping the frequency constant, what happens to the number of emitted electrons in the photoelectric effect?
A.
It doubles
B.
It remains the same
C.
It is halved
D.
It becomes zero
Solution
Doubling the intensity of light increases the number of photons incident on the surface, which in turn increases the number of emitted electrons, assuming the frequency is above the threshold frequency.
Q. If the intensity of light is doubled while keeping the frequency constant, what happens to the number of emitted electrons?
A.
It doubles
B.
It remains the same
C.
It is halved
D.
It becomes zero
Solution
Doubling the intensity of light increases the number of photons incident on the surface, which in turn increases the number of emitted electrons, assuming the frequency is above the threshold frequency.
Q. If the work function of a metal is 4.5 eV, what is the threshold wavelength for the photoelectric effect?
A.
400 nm
B.
500 nm
C.
600 nm
D.
700 nm
Solution
The threshold wavelength can be calculated using the equation λ = hc/φ. Substituting h = 4.14 x 10^-15 eV·s, c = 3 x 10^8 m/s, and φ = 4.5 eV gives λ ≈ 400 nm.
