# An electron of mass m with an initial velocity $$\overrightarrow v= v_0\hat i$$$\stackrel{}{}$$$( v_o > 0 )$$ enters in an electric field $$\overrightarrow E = -E_0 \hat i$$$$(E_0 = \text{constant}>0)$$ at $$t=0$$. If $$\lambda_0$$${\mathrm{}}_{}$, is its de-Broglie wavelength initially, then what will be its de-Broglie wavelength at time $$t$$? 1. $$\frac{\lambda_0}{\left(1+ \frac{eE_0}{mv_0}t\right)}$$ 2. $$\lambda_0\left(1+ \frac{eE_0}{mv_0}t\right)$$ 3. $$\lambda_0 t$$ 4. $$\lambda_0$$

Subtopic:  De-broglie Wavelength |
67%
From NCERT
NEET - 2018
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When the light of frequency $$2\nu_0$$ (where $$\nu_0$$ is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is $$v_1$$. When the frequency of the incident radiation is increased to $$5\nu_0,$$ the maximum velocity of electrons emitted from the same plate is $$v_2.$$ What will be the ratio of $$v_1$$ to $$v_2$$?

 1 $$1:2$$ 2 $$1:4$$ 3 $$4:1$$ 4 $$2:1$$
Subtopic:  Einstein's Photoelectric Equation |
73%
From NCERT
NEET - 2018
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For photoelectric emission from certain metals, the cutoff frequency is $$\nu$$. If radiation of frequency $$2\nu$$$\mathrm{}$ impinges on the metal plate, the maximum possible velocity of the emitted electron will be:
($$m$$ is the electron mass)

 1 $$\sqrt{\frac{h\nu}{m}}$$ 2 $$\sqrt{\frac{2h\nu}{m}}$$ 3 $$2\sqrt{\frac{h\nu}{m}}$$ 4 $$\sqrt{\frac{h\nu}{2m}}$$
Subtopic:  Einstein's Photoelectric Equation |
83%
From NCERT
AIPMT - 2013
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Light of two different frequencies, whose photons have energies of $$1$$ eV and $$2.5$$ eV respectively, illuminates a metallic surface whose work function is $$0.5$$ eV successively. The ratio of maximum speeds of emitted electrons will be:
1. $$1:2$$
2. $$1:1$$
3. $$1:5$$
4. $$1:4$$
Subtopic:  Einstein's Photoelectric Equation |
75%
From NCERT
AIPMT - 2011
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A $$5$$ W emits monochromatic light of wavelength $$5000~\mathring{A}$$. When placed $$0.5$$ m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved $$1.0$$ m away, the number of photoelectrons liberated is reduced by a factor of?
1. $$4$$
2. $$8$$
3. $$16$$
4. $$2$$

Subtopic:  Electron Emission |
71%
From NCERT
AIPMT - 2007
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The figure shows different graphs between stopping potential $$V_0$$ and frequency ($$\nu$$) for the photosensitive surfaces of cesium, potassium, sodium and lithium. The plots are parallel.

 1 Cesium 2 Potassium 3 Sodium 4 Lithium
The correct ranking of the targets according to their work function first will be:
 1 (i) > (ii) > (iii) > (iv) 2 (i) > (iii) > (ii) > (iv) 3 (iv) > (iii) > (ii) > (i) 4 (i) = (iii) > (ii) = (iv)
Subtopic:  Photoelectric Effect: Experiment |
74%
From NCERT
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The value of stopping potential in the following diagram is given by:

 1 $$-4$$ V 2 $$-3$$ V 3 $$-2$$ V 4 $$-1$$ V
Subtopic:  Photoelectric Effect: Experiment |
90%
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If in a photoelectric experiment, the wavelength of incident radiation is reduced from $$6000~\mathring{A}$$ to $$4000~\mathring{A}$$, then:
 1 The stopping potential will decrease. 2 The stopping potential will increase. 3 The kinetic energy of emitted electrons will decrease. 4 The value of the work function will decrease.
Subtopic:  Photoelectric Effect: Experiment |
75%
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The stopping potential for photoelectrons:

 1 does not depend on the frequency of the incident light. 2 does not depend upon the nature of the cathode material. 3 depends on both the frequency of the incident light and the nature of the cathode material. 4 depends upon the intensity of the incident light.
Subtopic:  Photoelectric Effect: Experiment |
72%
From NCERT
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A photocell is receiving light from a source placed at a distance of $$1$$ m. If the same source is placed at a distance of $$2$$ m, then the ejected electron:
 1 moves with one-fourth of energy as that of the initial energy. 2 moves with one-fourth of momentum as that of the initial momentum. 3 will be half in number. 4 will be one-fourth in number.
Subtopic:  Electron Emission |
65%
From NCERT
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