1
JEE Main 2018 (Online) 16th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
If the area of the region bounded by the curves, $$y = {x^2},y = {1 \over x}$$ and the lines y = 0 and x= t (t >1) is 1 sq. unit, then t is equal to :
A
$${e^{{3 \over 2}}}$$
B
$${4 \over 3}$$
C
$${3 \over 2}$$
D
$${e^{{2 \over 3}}}$$
2
JEE Main 2018 (Online) 16th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A heating element has a resistance of 100 $$\Omega $$ at room temperature. When it is connected to a supply of 220 V, a steady current of 2 A passes in it and temperature is 500oC more than room temperature. what is the temperature coefficient of resistance of the heating element ?
A
0.5 $$ \times $$ 10$$-$$4 oC$$-$$1
B
5 $$ \times $$ 10$$-$$4 oC$$-$$1
C
1 $$ \times $$ 10$$-$$4 oC$$-$$1
D
2 $$ \times $$ 10$$-$$4 oC$$-$$1
3
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
4
JEE Main 2018 (Online) 16th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The de-Broglie wavelength ($$\lambda $$B) associated with the electron orbiting in the second excited state of hydrogen atom is related to that in the ground state ($$\lambda $$G) by :
A
$$\lambda $$B = 2$$\lambda $$G
B
$$\lambda $$B = 3$$\lambda $$G
C
$$\lambda $$B = $$\lambda $$G/2
D
$$\lambda $$B = $$\lambda $$G/3
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