1
JEE Main 2020 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The electric fields of two plane electromagnetic plane waves in vacuum are given by
$$\overrightarrow {{E_1}} = {E_0}\widehat j\cos \left( {\omega t - kx} \right)$$ and
$$\overrightarrow {{E_2}} = {E_0}\widehat k\cos \left( {\omega t - ky} \right)$$
At t = 0, a particle of charge q is at origin with
a velocity $$\overrightarrow v = 0.8c\widehat j$$ (c is the speed of light in vacuum). The instantaneous force experienced by the particle is :
A
$${E_0}q\left( {0.8\widehat i - \widehat j + 0.4\widehat k} \right)$$
B
$${E_0}q\left( { - 0.8\widehat i + \widehat j + \widehat k} \right)$$
C
$${E_0}q\left( {0.8\widehat i + \widehat j + 0.2\widehat k} \right)$$
D
$${E_0}q\left( {0.4\widehat i - 3\widehat j + 0.8\widehat k} \right)$$
2
JEE Main 2020 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Consider a sphere of radius R which carries a uniform charge density $$\rho $$. If a sphere of radius $${{R \over 2}}$$ is carved out of it, as shown, the ratio $${{\left| {\overrightarrow {{E_A}} } \right|} \over {\left| {\overrightarrow {{E_B}} } \right|}}$$ of magnitude of electric field $${\overrightarrow {{E_A}} }$$ and $${\overrightarrow {{E_B}} }$$, respectively, at points A and B due to the remaining portion is : JEE Main 2020 (Online) 9th January Morning Slot Physics - Electrostatics Question 143 English
A
$${{17} \over {54}}$$
B
$${{18} \over {54}}$$
C
$${{18} \over {34}}$$
D
$${{21} \over {34}}$$
3
JEE Main 2020 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A body A of mass m is moving in a circular orbit of radius R about a planet. Another body B of mass $${m \over 2}$$ collides with A with a velocity which is half $$\left( {{{\overrightarrow v } \over 2}} \right)$$ the instantaneous velocity$${\overrightarrow v }$$ of A. The collision is completely inelastic. Then, the combined body :
A
starts moving in an elliptical orbit around the planet.
B
Falls vertically downwards towards the planet
C
Escapes from the Planet's Gravitational field.
D
continues to move in a circular orbit
4
JEE Main 2020 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Consider a force $$\overrightarrow F = - x\widehat i + y\widehat j$$ . The work done by this force in moving a particle from point A(1, 0) to B(0, 1) along the line segment is : (all quantities are in SI units) JEE Main 2020 (Online) 9th January Morning Slot Physics - Work Power & Energy Question 83 English
A
2
B
$${1 \over 2}$$
C
1
D
$${3 \over 2}$$
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