1
JEE Main 2017 (Online) 8th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
In a certain region static electric and magnetic fields exist. The magnetic field is given by $$\overrightarrow B = {B_0}\left( {\widehat i + 2\widehat j - 4\widehat k} \right)$$ . If a test charge moving with a velocity $$\overrightarrow \upsilon = {\upsilon _0}\left( {3\widehat i - \widehat j + 2\widehat k} \right)$$ experiences no force in that region, then the electric field in the region, in SI units, is :
A
$$\overrightarrow E = - {\upsilon _0}\,{B_0}\left( {3\widehat i - 2\widehat j - 4\widehat k} \right)$$
B
$$\overrightarrow E = - {\upsilon _0}\,{B_0}\left( {\widehat i + \widehat j + 7\widehat k} \right)$$
C
$$\overrightarrow E = {\upsilon _0}\,{B_0}\left( {14\widehat j + 7\widehat k} \right)$$
D
$$\overrightarrow E = - {\upsilon _0}\,{B_0}\left( {14\widehat j + 7\widehat k} \right)$$
2
JEE Main 2017 (Online) 8th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
In a physical balance working on the principle of moments, when 5 mg weight is placed on the left pan, the beam becomes horizontal. Both the empty pans of the balance are of equal mass. Which of the following statements is correct ?
A
Left arm is longer than the right arm
B
Both the arms are of same length
C
Left arm is shorter than the right arm
D
Every object that is weighed using this balance appears lighter than its actual weight.
3
JEE Main 2017 (Online) 8th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
A potentiometer PQ is set up to compare two resistances as shown in the figure. The ammeter A in the circuit reads 1.0 A when two way key K3 is open. The balance point is at a length $$\ell $$1 cm from P when two way key K3 is plugged in between 2 and 1, while the balance point is at a length $$\ell $$2 cm from P when key K3 is plugged in between 3 and 1. The ratio of two resistances $${{{R_1}} \over {{R_2}}}$$, is found to be :

JEE Main 2017 (Online) 8th April Morning Slot Physics - Current Electricity Question 248 English
A
$${{{l_1}} \over {{l_1} + {l_2}}}$$
B
$${{{l_2}} \over {{l_2} - {l_1}}}$$
C
$${{{l_1}} \over {{l_1} - {l_2}}}$$
D
$${{{l_1}} \over {{l_2} - {l_1}}}$$
4
JEE Main 2017 (Online) 8th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A uniform disc of radius R and mass M is free to rotate only about its axis. A string is wrapped over its rim and a body of mass m is tied to the free end of the string as shown in the figure. The body is released from rest. Then the acceleration of the body is :

JEE Main 2017 (Online) 8th April Morning Slot Physics - Rotational Motion Question 162 English
A
$${{2\,\,mg} \over {2\,m + M}}$$
B
$${{2\,\,Mg} \over {2\,m + M}}$$
C
$${{2\,\,mg} \over {2\,M + m}}$$
D
$${{2\,\,Mg} \over {2\,M + M}}$$
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