1
JEE Main 2019 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
For a uniformly charged ring of radius R, the electric field on its axis has the largest magnitude at a distance h from its center. Then value of h is :
A
$${R \over {\sqrt 5 }}$$
B
$${R \over {\sqrt 2 }}$$
C
R
D
R$$\sqrt 2 $$
2
JEE Main 2019 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A heavy ball of mass M is suspendeed from the ceiling of a car by a light string of mass m (m < < M). When the car is at rest, the speed of transverse waves in the string is 60 ms$$-$$1. When the car has acceleration a, the wave-speed increases to 60.5 ms$$-$$1. The value of a, in terms of gravitational acceleration g, is closest to :
A
$${g \over {30}}$$
B
$${g \over 5}$$
C
$${g \over 10}$$
D
$${g \over 20}$$
3
JEE Main 2019 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Consider a tank made of glass(refractive index 1.5) with a thick bottom. It is filled with a liquid of refractive index $$\mu $$. A student finds that, irrespective of what the incident angle i (see figure) is for a beam of light entering the liquid, the light reflected from the liquid glass interface is never completely polarized. For this to happen, the minimum value of $$\mu $$ is :

JEE Main 2019 (Online) 9th January Morning Slot Physics - Wave Optics Question 93 English
A
$$\sqrt {{5 \over 3}} $$
B
$${3 \over {\sqrt 5 }}$$
C
$${5 \over {\sqrt 3 }}$$
D
$${4 \over 3}$$
4
JEE Main 2019 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A copper wire is stretched to make it 0.5% longer. The percentage change in its electrical resistance if its volume remains unchanged is :
A
2.0 %
B
2.5 %
C
1.0 %
D
0.5 %
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