1
JEE Main 2018 (Online) 16th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Both the nucleus and the atom of some element arein their respective first excited states. They get de-excted by emitting photons of wavelengths $$\lambda $$N, $$\lambda $$A respectively. The ratio $${{{}^\lambda N} \over {{}^\lambda A}}$$is closest to :
A
10$$-$$6
B
10
C
10$$-$$10
D
10$$-$$1
2
JEE Main 2018 (Online) 16th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
At some instant, a radioactive sample S1 having an activity 5 $$\mu $$Ci has twice the number of nuclei as another sample S2 which has an activity of 10 $$\mu $$Ci. The half lives of S1 and S2 are :
A
20 years and 5 years, respectively
B
20 years and 10years, respectively
C
5 years and 20 years, respectively
D
10 years and 20 years, respectively
3
JEE Main 2018 (Online) 16th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
A carrier wave of peak voltage 14 V is used for transmitting a message signal. The peak voltage of modulating signal given to achieve a modulation index of 80% will be :
A
7 V
B
28 V
C
11.2 V
D
22.4 V
4
JEE Main 2018 (Online) 16th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The end correction of a resonance column is 1 cm. If the shortest length resonating with the tunning fork is 10 cm, the next resonating length should be :
A
28 cm
B
32 cm
C
36 cm
D
40 c
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