It means matter and radiation both show wave and particle nature under different conditions.
Light can be a wave (like rainbow) or particle (like laser beam hitting electrons).
When light of suitable frequency falls on a metal surface, it emits electrons.
Where:
PYQ Type: Formula MCQ
Minimum frequency needed to eject an electron.
PYQ Type: Concept MCQ
For matter waves associated with moving particles.
PYQ Type: Numerical formula MCQ
Characteristics of light behavior.
PYQ Type: Concept theory MCQ
Year Question Asked
2021 Shift 2: Unit of Planck’s constant (J·s)
2022 Shift 3: de Broglie formula MCQ
2023 Feb Shift 1: Photoelectric equation conceptual MCQ
| Concept | Formula |
|---|---|
| Photoelectric | \( h\nu = W + K.E. \) |
| Cutoff frequency | \( \nu_0 = \frac{W}{h} \) |
| de Broglie wavelength | \( \lambda = \frac{h}{p} \) |
| Momentum | \( p = mv \) |
| Concept | GenZ Example |
|---|---|
| Light knocks electrons out | UV light triggering sensors |
| de Broglie waves for electrons | Like wave-particle dual personality |
| Cut-off frequency | No photoelectric effect if light’s too low frequency |
Focus Areas:
Q1. SI unit of Planck’s constant is:
a) J·s
b) Wb
c) Tm/A
d) A·m
Ans: a
Q2. Photoelectric equation is:
a) \( h\nu = W + K.E. \)
b) \( E = mc^2 \)
c) \( V = IR \)
d) \( q = mc\Delta T \)
Ans: a
Q3. de Broglie wavelength formula is:
a) \( \lambda = \frac{h}{p} \)
b) \( p = \frac{h}{\lambda} \)
c) \( E = h\nu \)
d) None
Ans: a
Q4. If frequency is below cut-off frequency:
a) No photoelectric emission
b) Emission doubles
c) Photon energy increases
d) None
Ans: a
Q5. SI unit of de Broglie wavelength is:
a) Tesla
b) Meter
c) Joule
d) Henry
Ans: b
Q6. de Broglie concept applies to:
a) Only light
b) Only electron
c) All moving particles
d) None
Ans: c
Q7. Which shows wave-particle duality?
a) Light only
b) Matter only
c) Both light and matter
d) None
Ans: c
Q8. Maximum kinetic energy in photoelectric effect depends on:
a) Intensity
b) Frequency
c) Surface area
d) All
Ans: b
Q9. Cut-off frequency is:
a) Minimum frequency to emit photoelectrons
b) Maximum allowed frequency
c) Average frequency
d) None
Ans: a
Q10. When frequency increases in photoelectric effect:
a) K.E. increases
b) Number of electrons increases
c) Both increase
d) Neither
Ans: a