1
JEE Main 2020 (Online) 8th January Morning Slot
+4
-1
When photon of energy 4.0 eV strikes the surface of a metal A, the ejected photoelectrons have maximum kinetic energy TA eV end de-Broglie wavelength $$\lambda _A$$. The maximum kinetic energy of photoelectrons liberated from another metal B by photon of energy 4.50 eV is TB = (TA – 1.5) eV. If the de-Broglie wavelength of these photoelectrons $$\lambda _B$$ = 2$$\lambda _A$$, then the work function of metal B is :
A
1.5eV
B
4eV
C
2eV
D
3eV
2
JEE Main 2020 (Online) 8th January Morning Slot
+4
-1
The graph which depicts the results of Rutherford gold foil experiment with $$\alpha$$-particales is :
$$\theta$$ : Scattering angle
Y : Number of scattered $$\alpha$$-particles detected (Plots are schematic and not to scale)
A
B
C
D
3
JEE Main 2020 (Online) 7th January Morning Slot
+4
-1
The time period of revolution of electron in its ground state orbit in a hydrogen atom is 1.6 $$\times$$ 10-16 s. The frequency of revolution of the electron in its first excited state (in s-1) is :
A
5.6 $$\times$$ 1012
B
1.6 $$\times$$ 1014
C
7.8 $$\times$$ 1014
D
6.2 $$\times$$ 1015
4
JEE Main 2019 (Online) 12th April Evening Slot
+4
-1
The electron in a hydrogen atom first jumps from the third excited state to the second excited state and subsequently to the first excited state. The ratio of the respective wavelengths, $${{{\lambda _1}} \over {{\lambda _2}}}$$, of the photons emitted in this process is :
A
$${{22} \over 5}$$
B
$${7 \over 5}$$
C
$${9 \over 7}$$
D
$${{20} \over 7}$$
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