1
JEE Main 2023 (Online) 1st February Evening Shift
+4
-1

The threshold frequency of a metal is $$f_{0}$$. When the light of frequency $$2 f_{0}$$ is incident on the metal plate, the maximum velocity of photoelectrons is $$v_{1}$$. When the frequency of incident radiation is increased to $$5 \mathrm{f}_{0}$$, the maximum velocity of photoelectrons emitted is $$v_{2}$$. The ratio of $$v_{1}$$ to $$v_{2}$$ is :

A
$$\frac{v_{1}}{v_{2}}=\frac{1}{2}$$
B
$$\frac{v_{1}}{v_{2}}=\frac{1}{16}$$
C
$$\frac{v_{1}}{v_{2}}=\frac{1}{4}$$
D
$$\frac{v_{1}}{v_{2}}=\frac{1}{8}$$
2
JEE Main 2023 (Online) 31st January Evening Shift
+4
-1
If the two metals $\mathrm{A}$ and $\mathrm{B}$ are exposed to radiation of wavelength $350 \mathrm{~nm}$. The work functions of metals $\mathrm{A}$ and $\mathrm{B}$ are $4.8 \mathrm{eV}$ and $2.2 \mathrm{eV}$. Then choose the correct option.
A
Metal B will not emit photo-electrons
B
Both metals $\mathrm{A}$ and $\mathrm{B}$ will not emit photo-electrons
C
Metal A will not emit photo-electrons
D
Both metals A and B will emit photo-electrons
3
JEE Main 2023 (Online) 31st January Morning Shift
+4
-1

Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R

Assertion A : The beam of electrons show wave nature and exhibit interference and diffraction.

Reason R : Davisson Germer Experimentally verified the wave nature of electrons.

In the light of the above statements, choose the most appropriate answer from the options given below :

A
A is not correct but R is correct.
B
Both A and R are correct and R is the correct explanation of A
C
Both A and R are correct but R is Not the correct explanation of A
D
A is correct but R is not correct
4
JEE Main 2023 (Online) 31st January Morning Shift
+4
-1

If a source of electromagnetic radiation having power $$15 \mathrm{~kW}$$ produces $$10^{16}$$ photons per second, the radiation belongs to a part of spectrum is.

(Take Planck constant $$h=6 \times 10^{-34} \mathrm{Js}$$ )

A
Gamma rays
B
C
Micro waves
D
Ultraviolet rays
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