1
JEE Main 2021 (Online) 18th March Morning Shift
MCQ (Single Correct Answer)
+4
-1
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$$-$$
2
JEE Main 2021 (Online) 17th March Evening Shift
MCQ (Single Correct Answer)
+4
-1
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
$$v_1^2 - v_2^2 = {{2h} \over m}[{f_1} - {f_2}]$$
3
JEE Main 2021 (Online) 17th March Morning Shift
MCQ (Single Correct Answer)
+4
-1
An electron of mass m and a photon have same energy E. The ratio of wavelength of electron to that of photon is : (c being the velocity of light)
A
$${1 \over c}{\left( {{{2m} \over E}} \right)^{1/2}}$$
B
$${1 \over c}{\left( {{E \over {2m}}} \right)^{1/2}}$$
C
$${\left( {{E \over {2m}}} \right)^{1/2}}$$
D
$$c{(2mE)^{1/2}}$$
4
JEE Main 2021 (Online) 16th March Evening Shift
MCQ (Single Correct Answer)
+4
-1
The de-Broglie wavelength associated with an electron and a proton were calculated by accelerating them through same potential of 100 V. What should nearly be the ratio of their wavelengths? (mp = 1.00727u me = 0.00055u)
A
41.4 : 1
B
(1860)2 : 1
C
1860 : 1
D
43 : 1
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