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Chapter 11: Dual Nature of Radiation

NCERT Solutions for CBSE Class 10 Physics — 36 solved questions with detailed explanations.

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Solved Questions

Q1. The work function of a metal is 2 eV. The threshold wavelength for photoelectric emission is approximately:

620 nm
310 nm
6200 nm
124 nm

Difficulty: Easy-Medium · Topic: Photoelectric Effect

Solution

λ₀ = hc/φ = 1240 eV·nm / 2 eV = 620 nm.

Q2. The de Broglie wavelength of an electron accelerated through a potential V is:

1.226/√V nm
12.26/√V Å
0.1226/√V nm
122.6/√V Å

Difficulty: Easy-Medium · Topic: de Broglie Wavelength

Solution

λ = h/√(2meV) = 12.26/√V Å for electrons.

Q3. In photoelectric effect, the stopping potential depends on:

Intensity of light
Frequency of light
Nature of collector
Area of emitter

Difficulty: Easy-Medium · Topic: Stopping Potential

Solution

Stopping potential V₀ = (hν - φ)/e. It depends on frequency, not intensity.

Q4. The maximum kinetic energy of photoelectrons emitted from a surface of work function 3 eV when light of energy 5 eV falls on it is:

Difficulty: Easy-Medium · Topic: KE of Photoelectrons

Solution

KE_max = hν - φ = 5 - 3 = 2 eV.

Q5. Light of energy 5 eV falls on metal with work function 2 eV. Maximum KE of photoelectrons is:

Difficulty: Easy-Medium · Topic: Photoelectric Effect

Solution

KE = hν - φ = 5 - 2 = 3 eV.

Q6. Light of energy 3 eV falls on metal with work function 1.5 eV. Maximum KE of photoelectrons is:

Difficulty: Easy-Medium · Topic: Photoelectric Effect

Solution

KE = hν - φ = 3 - 1.5 = 1.5 eV.

Q7. Light of energy 6 eV falls on metal with work function 3 eV. Maximum KE of photoelectrons is:

Difficulty: Easy-Medium · Topic: Photoelectric Effect

Solution

KE = hν - φ = 6 - 3 = 3 eV.

Q8. Light of energy 4 eV falls on metal with work function 2.5 eV. Maximum KE of photoelectrons is:

Difficulty: Easy-Medium · Topic: Photoelectric Effect

Solution

KE = hν - φ = 4 - 2.5 = 1.5 eV.

Q9. Light of energy 7 eV falls on metal with work function 4.5 eV. Maximum KE of photoelectrons is:

Difficulty: Easy-Medium · Topic: Photoelectric Effect

Solution

KE = hν - φ = 7 - 4.5 = 2.5 eV.

Q10. de Broglie wavelength of electron accelerated through 100 V is approximately:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V = 12.26/√100 = 1.226 Å.

Q11. de Broglie wavelength of electron accelerated through 150 V is approximately:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V = 12.26/√150 = 1.001 Å.

Q12. de Broglie wavelength of electron accelerated through 200 V is approximately:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V = 12.26/√200 = 0.867 Å.

Q13. de Broglie wavelength of electron accelerated through 400 V is approximately:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V = 12.26/√400 = 0.613 Å.

Q14. de Broglie wavelength of electron accelerated through 25 V is approximately:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V = 12.26/√25 = 2.452 Å.

Q15. de Broglie wavelength of electron accelerated through 50 V is approximately:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V = 12.26/√50 = 1.734 Å.

Q16. de Broglie wavelength of electron accelerated through 10000 V is approximately:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V = 12.26/√10000 = 0.123 Å.

Q17. de Broglie wavelength of electron at 50 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q18. de Broglie wavelength of electron at 75 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q19. de Broglie wavelength of electron at 100 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q20. de Broglie wavelength of electron at 125 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q21. de Broglie wavelength of electron at 150 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q22. de Broglie wavelength of electron at 175 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q23. de Broglie wavelength of electron at 200 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q24. de Broglie wavelength of electron at 225 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q25. de Broglie wavelength of electron at 250 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q26. de Broglie wavelength of electron at 275 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q27. de Broglie wavelength of electron at 300 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q28. de Broglie wavelength of electron at 325 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q29. de Broglie wavelength of electron at 350 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q30. de Broglie wavelength of electron at 375 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q31. de Broglie wavelength of electron at 400 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q32. de Broglie wavelength of electron at 425 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q33. de Broglie wavelength of electron at 450 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q34. de Broglie wavelength of electron at 475 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q35. de Broglie wavelength of electron at 500 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Q36. de Broglie wavelength of electron at 525 V is:

Difficulty: Easy-Medium · Topic: de Broglie

Solution

λ = 12.26/√V Å.

Other Chapters in Physics

Ch 1: Electric Charges & Fields Ch 2: Electrostatic Potential Ch 3: Current Electricity Ch 4: Moving Charges & Magnetism Ch 5: Magnetism & Matter Ch 6: Electromagnetic Induction Ch 7: Alternating Current Ch 8: Electromagnetic Waves Ch 9: Ray Optics Ch 10: Wave Optics Ch 12: Atoms Ch 13: Nuclei Ch 14: Semiconductor Electronics

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