1
JEE Main 2021 (Online) 17th March Evening Shift
+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
$$v_1^2 - v_2^2 = {{2h} \over m}[{f_1} - {f_2}]$$
2
JEE Main 2021 (Online) 16th March Morning Shift
+4
-1
The stopping potential in the context of photoelectric effect depends on the following property of incident electromagnetic radiation :
A
Phase
B
Frequency
C
Amnplitude
D
Intensity
3
JEE Main 2021 (Online) 26th February Evening Shift
+4
-1
The recoil speed of a hydrogen atom after it emits a photon in going from n = 5 state to n = 1 state will be :
A
4.34 m/s
B
2.19 m/s
C
3.25 m/s
D
4.17 m/s
4
JEE Main 2021 (Online) 26th February Morning Shift
+4
-1
Given below are two statements : one is labeled as Assertion A and the other is labelled as Reason R.

Assertion A : An electron microscope can achieve better resolving power than an optical microscope.

Reason R : The de Broglie's wavelength of the electrons emitted from an electron gun is much less than wavelength of visible light.

In the light of the above statements, choose the correct answer from the options given below :
A
A is false but R is true.
B
Both A and R are true but R is NOT the correct explanation of A.
C
Both A and R are true and R is the correct explanation of A.
D
A is true but R is false.
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