1
JEE Main 2017 (Online) 9th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
A signal is to be transmitted through a wave of wavelength $$\lambda $$, using a linear antenna. The length l of the antenna and effective power radiated Peff will be given respectively as :

(K is a constant of proportionality)
A
$$\lambda $$, Peff = K $$\left( {{1 \over \lambda }} \right)$$2
B
$${{\lambda \over 8}}$$, Peff = K $$\left( {{1 \over \lambda }} \right)$$
C
$${{\lambda \over 16}}$$, Peff = K $$\left( {{1 \over \lambda }} \right)$$3
D
$${{\lambda \over 5}}$$, Peff = K $$\left( {{1 \over \lambda }} \right)$$$${\left( {{1 \over \lambda }} \right)^{{1 \over 2}}}$$
2
JEE Main 2017 (Online) 9th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The acceleration of an electron in the first orbit of the hydrogen atom (n = 1) is :
A
$${{{h^2}} \over {{\pi ^2}{m^2}{r^3}}}$$
B
$${{{h^2}} \over {{8\pi ^2}{m^2}{r^3}}}$$
C
$${{{h^2}} \over {{4\pi ^2}{m^2}{r^3}}}$$
D
$${{{h^2}} \over {{4\pi }{m^2}{r^3}}}$$
3
JEE Main 2017 (Online) 9th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Imagine that a reactor converts all given mass into energy and that it operates at a power level of 109 watt. The mass of the fuel consumed per hour in the reactor will be : (velocity of light, c is 3×108 m/s)
A
0.96 gm
B
0.8 gm
C
4 $$ \times $$ 10$$-$$2 gm
D
6.6 $$ \times $$ 10$$-$$5 gm
4
JEE Main 2017 (Online) 9th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
In an experiment to determine the period of a simple pendulum of length 1 m, it is attached to different spherical bobs of radii r1 and r2 . The two spherical bobs have uniform mass distribution. If the relative difference in the periods, is found to be 5×10−4 s, the difference in radii, $$\left| {} \right.$$r1 $$-$$ r2 $$\left| {} \right.$$ is best given by :
A
1 cm
B
0.05 cm
C
0.5 cm
D
0.01 cm
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