1
JEE Main 2021 (Online) 20th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The radiation corresponding to 3 $$\to$$ 2 transition of a hydrogen atom falls on a gold surface to generate photoelectrons. The electrons are passed through a magnetic field of 5 $$\times$$ 10$$-$$4 T. Assume that the radius of the largest circular path followed by these electrons is 7 mm, the work function of the metal is : (Mass of electron = 9.1 $$\times$$ 10$$-$$31 kg)
A
1.36 eV
B
1.88 eV
C
0.82 eV
D
0.16 eV
2
JEE Main 2021 (Online) 18th March Evening Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
The speed of electrons in a scanning electron microscope is 1 $$\times$$ 107 ms-1. If the protons having the same speed are used instead of electrons, then the resolving power of scanning proton microscope will be changed by a factor of :
A
$${1 \over {1837}}$$
B
1837
C
$${\sqrt {1837} }$$
D
$${1 \over {\sqrt {1837} }}$$
3
JEE Main 2021 (Online) 18th March Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A particle is travelling 4 time as fast as an electron. Assuming the ratio of de-Broglie wavelength of a particle to that of electron is 2 : 1, the mass of the particle is :
A
$${1 \over {16}}$$ times the mass of e$$-$$
B
8 times the mass of e$$-$$
C
16 times the mass of e$$-$$
D
$${1 \over {8}}$$ times the mass of e$$-$$
4
JEE Main 2021 (Online) 17th March Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Two identical photocathodes receive the light of frequencies f1 and f2 respectively. If the velocities of the photo-electrons coming out are v1 and v2 respectively, then
A
$${v_1} - {v_2} = {\left[ {{{2h} \over m}({f_1} - {f_2})} \right]^{{1 \over 2}}}$$
B
$$v_1^2 + v_2^2 = {{2h} \over m}[{f_1} + {f_2}]$$
C
$${v_1} + {v_2} = {\left[ {{{2h} \over m}({f_1} + {f_2})} \right]^{{1 \over 2}}}$$
D
$$v_1^2 - v_2^2 = {{2h} \over m}[{f_1} - {f_2}]$$
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