1
JEE Main 2023 (Online) 31st January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The radius of electron's second stationary orbit in Bohr's atom is R. The radius of 3rd orbit will be
A
2.25R
B
$3 \mathrm{R}$
C
$\frac{\mathrm{R}}{3}$
D
$9 \mathrm{R}$
2
JEE Main 2023 (Online) 31st January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
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 Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The number of turns of the coil of a moving coil galvanometer is increased in order to increase current sensitivity by $50 \%$. The percentage change in voltage sensitivity of the galvanometer will be :
A
$0 \%$
B
$75 \%$
C
$100 \%$
D
$50 \%$
4
JEE Main 2023 (Online) 31st January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Match List I with List II

LIST I LIST II
A. Microwaves I. Physiotherapy
B. UV rays II. Treatment of cancer
C. Infra-red light III. Lasik eye surgery
D. X-ray IV. Aircraft navigation

Choose the correct answer from the options given below:
A
A - IV, B - III, C - I, D - II
B
A - II, B - IV, C - III, D - I
C
A - III, B - II, C - I, D - IV
D
A - IV, B - I, C - II, D - III
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