1
JEE Main 2021 (Online) 26th August Evening Shift
+4
-1
The de-Broglie wavelength of a particle having kinetic energy E is $$\lambda$$. How much extra energy must be given to this particle so that the de-Broglie wavelength reduces to 75% of the initial value?
A
$${1 \over 9}$$E
B
$${7 \over 9}$$E
C
E
D
$${16 \over 9}$$E
2
JEE Main 2021 (Online) 26th August Morning Shift
+4
-1
In a photoelectric experiment ultraviolet light of wavelength 280 nm is used with lithium cathode having work function $$\phi$$ = 2.5 eV. If the wavelength of incident light is switched to 400 nm, find out the change in the stopping potential. (h = 6.63 $$\times$$ 10$$-$$34 Js, c = 3 $$\times$$ 108 ms$$-$$1)
A
1.3 V
B
1.1 V
C
1.9 V
D
0.6 V
3
JEE Main 2021 (Online) 27th July Evening Shift
+4
-1
An electron and proton are separated by a large distance. The electron starts approaching the proton with energy 3 eV. The proton captures the electron and forms a hydrogen atom in second excited state. The resulting photon is incident on a photosensitive metal of threshold wavelength 4000$$\mathop A\limits^o$$. What is the maximum kinetic energy of the emitted photoelectron?
A
7.61 eV
B
1.41 eV
C
3.3 eV
D
No photoelectron would be emitted
4
JEE Main 2021 (Online) 25th July Evening Shift
+4
-1
An electron moving with speed v and a photon moving with speed c, have same D-Broglie wavelength. The ratio of kinetic energy of electron to that of photon is :
A
$${{3c} \over v}$$
B
$${v \over {3c}}$$
C
$${v \over {2c}}$$
D
$${{2c} \over v}$$
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