1
JEE Main 2021 (Online) 25th July Evening Shift
MCQ (Single Correct Answer)
+4
-1
When radiation of wavelength $$\lambda$$ is incident on a metallic surface, the stopping potential of ejected photoelectrons is 4.8 V. If the same surface is illuminated by radiation of double the previous wavelength, then the stopping potential becomes 1.6 V. The threshold wavelength of the metal is :
A
2$$\lambda$$
B
4$$\lambda$$
C
8$$\lambda$$
D
6$$\lambda$$
2
JEE Main 2021 (Online) 25th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
What should be the order of arrangement of de-Broglie wavelength of electron ($$\lambda$$e), an $$\alpha$$-particle ($$\lambda$$a) and proton ($$\lambda$$p) given that all have the same kinetic energy?
A
$$\lambda$$e = $$\lambda$$p = $$\lambda$$$$\alpha$$
B
$$\lambda$$e < $$\lambda$$p < $$\lambda$$$$\alpha$$
C
$$\lambda$$e > $$\lambda$$p > $$\lambda$$$$\alpha$$
D
$$\lambda$$e = $$\lambda$$p > $$\lambda$$$$\alpha$$
3
JEE Main 2021 (Online) 25th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
A particle of mass 4M at rest disintegrates into two particles of mass M and 3M respectively having non zero velocities. The ratio of de-Broglie wavelength of particle of mass M to that of mass 3M will be :
A
1 : 3
B
3 : 1
C
1 : $$\sqrt 3 $$
D
1 : 1
4
JEE Main 2021 (Online) 22th July Evening Shift
MCQ (Single Correct Answer)
+4
-1
An electron of mass me and a proton of mass mp are accelerated through the same potential difference. The ratio of the de-Broglie wavelength associated with the electron to that with the proton is
A
$${{{m_e}} \over {{m_p}}}$$
B
1
C
$${{{m_p}} \over {{m_e}}}$$
D
$$\sqrt {{{{m_p}} \over {{m_e}}}} $$
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