1
JEE Main 2019 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A plane electromagnetic wave of frequency 50 MHz travels in free space along the positive x-direction. At a particular point in space and time, $$\overrightarrow E = 6.3\widehat j\,V/m.$$ The corresponding magnetic field $$\overrightarrow {B,} $$ at that point will be :
A
18.9 $$ \times $$ 10$$-$$8 $$\widehat k$$T
B
2.1 $$ \times $$ 10$$-$$8 $$\widehat k$$T
C
6.3 $$ \times $$ 10$$-$$8 $$\widehat k$$T
D
18.9 $$ \times $$ 108 $$\widehat k$$T
2
JEE Main 2019 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A gas can be taken from A to B via two different processes ACB and ADB.

JEE Main 2019 (Online) 9th January Morning Slot Physics - Heat and Thermodynamics Question 291 English
When path ACB is used 60 J of heat flows into the system and 30 J of work is done by the system. If path ADB is used work done by the system is 10 J. The heat Flow into the system in path ADB is :
A
40 J
B
80 J
C
100 J
D
20 J
3
JEE Main 2019 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A rod, of length L at room temperature and uniform area of cross section A, is made of a metal having coefficient of linear expansion $$\alpha $$/oC. It is observed that an external compressive force F, is applied on each of its ends, prevents any change in the length of the rod, when its temperature rises by $$\Delta $$TK. Young's modulus, Y, for this metal is :
A
$${F \over {A\alpha \Delta T}}$$
B
$${F \over {A\alpha (\Delta T - 273)}}$$
C
$${F \over {2A\alpha \Delta T}}$$
D
$${{2F} \over {A\alpha \Delta T}}$$
4
JEE Main 2019 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A parallel plate capacitor is made of two square plates of side 'a', separated by a distance d (d < < a). The lower triangular portion is filled with a dielectric of dielectric constant K, as shown in the figure. Capacitance of this capacitor is :

JEE Main 2019 (Online) 9th January Morning Slot Physics - Capacitor Question 109 English
A
$${{K{ \in _0}{a^2}} \over {2d(K + 1)}}$$
B
$${{K{ \in _0}{a^2}} \over {d(K - 1)}}\ln K$$
C
$${{K{ \in _0}{a^2}} \over d}\ln K$$
D
$${1 \over 2}{{K{ \in _0}{a^2}} \over d}$$
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