1
JEE Main 2019 (Online) 9th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
In the given circuit the the internal resistance of the 18 V cell is negligible. If R1 = 400 $$\Omega $$, R3 = 100 $$\Omega $$ and R4 = 500 $$\Omega $$ and the reading of an ideal voltmeter across R4 is 5V, then the value of R2 will be :

JEE Main 2019 (Online) 9th January Evening Slot Physics - Current Electricity Question 235 English
A
300 $$\Omega $$
B
450 $$\Omega $$
C
550 $$\Omega $$
D
230 $$\Omega $$
2
JEE Main 2019 (Online) 9th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A parallel plate capacitor with square plates is filled with four dielecytrics of dielectrics constants K1, K2, K3, K4 arranged as shown in the figure. The effective dielectric constant K will be :

JEE Main 2019 (Online) 9th January Evening Slot Physics - Capacitor Question 108 English
A
$$K = {{{K_1}{K_2}} \over {{K_1} + {K_2}}} + {{{K_3}{K_4}} \over {{K_3} + {K_4}}}$$
B
$$K = {{\left( {{K_1} + {K_2}} \right)\left( {{K_3} + {K_4}} \right)} \over {2\left( {{K_1} + {K_2} + {K_3} + {K_4}} \right)}}$$
C
$$K = {{\left( {{K_1} + {K_2}} \right)\left( {{K_3} + {K_4}} \right)} \over {{K_1} + {K_2} + {K_3} + {K_4}}}$$
D
$$K = {{\left( {{K_1} + {K_4}} \right)\left( {{K_2} + {K_3}} \right)} \over {2\left( {{K_1} + {K_2} + {K_3} + {K_4}} \right)}}$$
3
JEE Main 2019 (Online) 9th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A rod of length 50 cm is pivoted at one end. It is raised such that if makes an angle of 30o from the horizontal as shown and released from rest. Its angular speed when it passes through the horizontal (in rad s$$-$$1) will be (g = 10 ms$$-$$2)

JEE Main 2019 (Online) 9th January Evening Slot Physics - Rotational Motion Question 154 English
A
$$\sqrt {{{30} \over 7}} $$
B
$$\sqrt {30} $$
C
$${{\sqrt {20} } \over 3}$$
D
$${{\sqrt {30} } \over 2}$$
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