Q18.Two radioactive elements 𝐴 and 𝐵 initially have same number of atoms. The half life of 𝐴 is same as the average life of 𝐵. If 𝜆𝐴 and 𝜆𝐵 are decay constants of 𝐴 and 𝐵 respectively, then choose the correct relation from the given options. (1) 𝜆𝐴ln2 = 𝜆𝐵 (2) 𝜆𝐴= 𝜆𝐵 (3) 𝜆𝐴= 𝜆𝐵ln2 (4) 𝜆𝐴= 2𝜆𝐵
What This Question Tests
This question requires solving simultaneous equations derived from Einstein's photoelectric equation for two different wavelengths and stopping potentials to find the threshold wavelength.
Concepts Tested
Formulas Used
eV₀ = hc/λ - φ₀
φ₀ = hc/λ_th
📚 NCERT Sections This Tests
12.1 — (A) No Different From
Physics Class 12 · Chapter 12
12.1 (a) No different from (b) Thomson’s model; Rutherford’s model (c) Rutherford’s model (d) Thomson’s model; Rutherford’s model (e) Both the models
11.6 — The Threshold Frequency For A Certain Metal Is 3.3 × 1014 Hz. If Light
Physics Class 12 · Chapter 11
11.6 The threshold frequency for a certain metal is 3.3 × 1014 Hz. If light of frequency 8.2 × 1014 Hz is incident on the metal, predict the cut- off voltage for the photoelectric emission.
11.8 — Light Of Frequency 7.21 × 1014 Hz Is Incident On A Metal Surface.
Physics Class 12 · Chapter 11
11.8 Light of frequency 7.21 × 1014 Hz is incident on a metal surface. Electrons with a maximum speed of 6.0 × 105 m/s are ejected from the surface. What is the threshold frequency for photoemission of electrons?
📋 Question Details
- Chapter
- Dual Nature of Matter
- Topic
- Photoelectric effect
- Year
- 2023
- Shift
- 11 Apr Shift 1
- Q Number
- Q18
- Type
- MCQ
- NCERT Ref
- Class 12 Physics Ch 11: Dual Nature of Radiation and Matter
More from this Chapter
Q68.Sodium and copper have work functions 2.3eV and 4.5eV respectively. Then the ratio of the wave lengths is nearest to JEE Main 2002 JEE Main Previous Year Paper (1) 1 : 2 (2) 4 : 1 (3) 2 : 1 (4) 1 : 4
Q69.Formation of covalent bonds in compounds exhibits (1) wave nature of electron (2) particle nature of electron (3) both wave and particle nature of electron (4) none of these
Q80.Uncertainity in position of a minute particle of mass 25 g in space is 10−5 m. What is the uncertainity in its velocity (in ms−1)? ( h = 6.6 × 10−34Js) (1) 2.1 × 10−34 (2) 0.5 × 10−34 (3) 2.1 × 10−28 (4) 0.5 × 10−23 Q81. β - particle is emitted in radioactivity by (1) conversion of proton to neutron (2) from outermost orbit (3) conversion of neutron to proton (4) β-particle is not emitted
Q27.The earth radiates in the infra-red region of the spectrum. The spectrum is correctly given by (1) Rayleigh Jeans law (2) Planck's law of radiation (3) Stefan's law of radiation (4) Wien's law