1
JEE Main 2021 (Online) 26th August Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A light beam is described by $$E = 800\sin \omega \left( {t - {x \over c}} \right)$$. An electron is allowed to move normal to the propagation of light beam with a speed of 3 $$\times$$ 107 ms$$-$$1. What is the maximum magnetic force exerted on the electron?
A
1.28 $$\times$$ 10$$-$$18 N
B
1.28 $$\times$$ 10$$-$$21 N
C
12.8 $$\times$$ 10$$-$$17 N
D
12.8 $$\times$$ 10$$-$$18 N
2
JEE Main 2021 (Online) 26th August Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The two thin coaxial rings, each of radius 'a' and having charges +Q and $$-$$Q respectively are separated by a distance of 's'. The potential difference between the centres of the two rings is :
A
$${Q \over {2\pi {\varepsilon _0}}}\left[ {{1 \over a} + {1 \over {\sqrt {{s^2} + {a^2}} }}} \right]$$
B
$${Q \over {4\pi {\varepsilon _0}}}\left[ {{1 \over a} + {1 \over {\sqrt {{s^2} + {a^2}} }}} \right]$$
C
$${Q \over {4\pi {\varepsilon _0}}}\left[ {{1 \over a} - {1 \over {\sqrt {{s^2} + {a^2}} }}} \right]$$
D
$${Q \over {2\pi {\varepsilon _0}}}\left[ {{1 \over a} - {1 \over {\sqrt {{s^2} + {a^2}} }}} \right]$$
3
JEE Main 2021 (Online) 26th August Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
If you are provided a set of resistances 2$$\Omega$$, 4$$\Omega$$, 6$$\Omega$$ and 8$$\Omega$$. Connect these resistances so as to obtain an equivalent resistance of $${{46} \over 3}$$$$\Omega$$.
A
4$$\Omega$$ and 6$$\Omega$$ are in parallel with 2$$\Omega$$ and 8$$\Omega$$ in series
B
6$$\Omega$$ and 8$$\Omega$$ are in parallel with 2$$\Omega$$ and 4$$\Omega$$ in series
C
2$$\Omega$$ and 6$$\Omega$$ are in parallel with 4$$\Omega$$ and 8$$\Omega$$ in series
D
2$$\Omega$$ and 4$$\Omega$$ are in parallel with 6$$\Omega$$ and 8$$\Omega$$ in series
4
JEE Main 2021 (Online) 26th August Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The solid cylinder of length 80 cm and mass M has a radius of 20 cm. Calculate the density of the material used if the moment of inertia of the cylinder about an axis CD parallel to AB as shown in figure is 2.7 kg m2.

JEE Main 2021 (Online) 26th August Evening Shift Physics - Rotational Motion Question 70 English
A
14.9 kg/m3
B
7.5 $$\times$$ 101 kg/m3
C
7.5 $$\times$$ 102 kg/m3
D
1.49 $$\times$$ 102 kg/m3
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