1
JEE Main 2019 (Online) 10th April Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
In free space, a particle A of charge 1$$\mu $$C is held fixed at a point P. Another particle B of the same charge and mass 4$$\mu $$g is kept at a distance of 1 mm from P. If B is released, then its velocity at a distance of 9 mm from P is : $$\left[ {Take\,{1 \over {4\pi { \in _0}}} = 9 \times {{10}^9}N{m^2}{C^{ - 2}}} \right]$$
A
1.0 m/s
B
6.32 $$ \times $$ 104 m/s
C
2.0 $$ \times $$ 103 m/s
D
1.5 $$ \times $$ 102 m/s
2
JEE Main 2019 (Online) 10th April Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
When heat Q is supplied to a diatomic gas of rigid molecules, at constant volume its temperature increases by $$\Delta $$T. the heat required to produce the same change in temperature, at a constant pressure is :
A
$${7 \over 5}Q$$
B
$${3 \over 2}Q$$
C
$${2 \over 3}Q$$
D
$${5 \over 3}Q$$
3
JEE Main 2019 (Online) 10th April Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The elastic limit of brass is 379 MPa. What should be the minimum diameter of a brass rod if it is to support a 400 N load without exceeding its elastic limit?
A
1.16 mm
B
1.36 mm
C
1.00 mm
D
0.90 mm
4
JEE Main 2019 (Online) 10th April Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A 2 mW laser operates at wavelength of 500 nm. The number of photons that will be emitted per second is : [Given Planck's constant h = 6.6 × 10–34 Js, speed of light c = 3.0 × 108 m/s]
A
5 × 1015
B
1.5 × 1016
C
1 × 1016
D
2 × 1016
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