Dual Nature of Matter & Radiation Flashcards for NEET — 20 cards

First 8 of 20 Dual Nature of Matter & Radiation flashcards

Read the question, answer it in your head, then open the answer to check yourself.

1. Card 1 of 20

   What is the rest mass of a photon?

   Hint: Photons always move at the speed of light ($c$) in a vacuum.

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   Answer

   Zero.

2. Card 2 of 20

   Write the de Broglie wavelength relation for matter waves.

   Hint: Connects the wave property ($\lambda$) with the particle property ($p$).

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   Answer

   $\lambda = \frac{h}{p} = \frac{h}{mv}$

3. Card 3 of 20

   Express the de Broglie wavelength ($\lambda$) of a particle in terms of its kinetic energy ($K$).

   Hint: Substitute $p = \sqrt{2mK}$ into the de Broglie relation.

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   Answer

   $\lambda = \frac{h}{\sqrt{2mK}}$

4. Card 4 of 20

   What is the Work Function ($\Phi_0$) of a metal?

   Hint: It is measured in electron volts (eV) and depends on the nature of the metal.

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   Answer

   The minimum energy required by an electron to just escape from the metal surface.

5. Card 5 of 20

   What is the value of 1 electron volt (1 eV) in Joules?

   Hint: Kinetic energy gained by an electron accelerated through a 1V potential.

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   Answer

   $1 \text{ eV} = 1.602 \times 10^{-19} \text{ J}$

6. Card 6 of 20

   What was Hertz's observation regarding the photoelectric effect?

   Hint: Discovered during his experiments on electromagnetic waves.

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   Answer

   He observed that high-voltage sparks across the detector loop were enhanced when the emitter plate was illuminated by ultraviolet (UV) light.

7. Card 7 of 20

   Define Threshold Frequency ($\nu_0$).

   Hint: Corresponds to the work function: $\Phi_0 = h\nu_0$.

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   Answer

   The minimum frequency of incident radiation below which photoelectric emission is not possible, regardless of the light's intensity.

8. Card 8 of 20

   How does photoelectric current vary with the intensity of incident light?

   Hint: More intensity = more photons = more electrons emitted.

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   Answer