1
JEE Main 2019 (Online) 9th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Two point charges q1$$\left( {\sqrt {10} \mu C} \right)$$ and q2($$-$$ 25 $$\mu $$C) are placed on the x-axis at x = 1 m and x = 4 m respectively. The electric field (in V/m) at a point y = 3 m on y-axis is,
[take $${1 \over {4\pi { \in _0}}}$$ = 9 $$ \times $$ 109 Nm2C$$-$$2]
A
$$\left( {63\widehat i - 27\widehat j} \right) \times {10^2}$$
B
$$\left( { - 63\widehat i + 27\widehat j} \right) \times {10^2}$$
C
$$\left( {81\widehat i - 81\widehat j} \right) \times {10^2}$$
D
$$\left( { - 81\widehat i + 81\widehat j} \right) \times {10^2}$$
2
JEE Main 2019 (Online) 9th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A 15 g mass of nitrogen gas is enclosed in a vessel at a temperature 27oC. Amount of heat transferred to the gas, so that rms velocity of molecules is doubled, is about : [Take R = 8.3 J/K mole]
A
0.9 kJ
B
6 kJ
C
10 kJ
D
14 kJ
3
JEE Main 2019 (Online) 9th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Charge is distributed within a sphere of radius R with a volume charge density $$\rho \left( r \right) = {A \over {{r^2}}}{e^{ - {{2r} \over s}}},$$ where A and a are constants. If Q is the total charge of this charge distribution, the radius R is :
A
a log $$\left( {1 - {Q \over {2\pi aA}}} \right)$$
B
$${a \over 2}$$ log $$\left( {{1 \over {1 - {Q \over {2\pi aA}}}}} \right)$$
C
a log $$\left( {{1 \over {1 - {Q \over {2\pi aA}}}}} \right)$$
D
$${a \over 2}$$ log $$\left( {1 - {Q \over {2\pi aA}}} \right)$$
4
JEE Main 2019 (Online) 9th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A power transmission line feeds input power at 2300 V to a srep down transformer with its primary windings having 4000 turns. The output power is delivered at 230 V by the transformer. If the current in the primary of the transformer is 5A and its efficiency is 90%, the output current would be :
A
50 A
B
45 A
C
35 A
D
25 A

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