1
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A circuit to verify Ohm's law uses ammeter and voltmeter in series or parallel connected correctly to the resistor. In the circuit :
A
Ammeter is always connected in series and voltmeter in parallel
B
Both ammeter and voltmeter must be connected in series
C
Both ammeter and voltmeter must be connected in parallel
D
Ammeter is always used in parallel and voltmeter is series
2
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Two identical electric point dipoles have dipole moments $${\overrightarrow p _1} = p\widehat i$$ and $${\overrightarrow p _2} = - p\widehat i$$ and are held on the x axis at distance '$$a$$' from each other. When released, they move along the x-axis with the direction of their dipole moments remaining unchanged. If the mass of each dipole is 'm', their speed when they are infinitely far apart is :
A
$${p \over a}\sqrt {{3 \over {2\pi { \in _0}ma}}} $$
B
$${p \over a}\sqrt {{1 \over {\pi { \in _0}ma}}} $$
C
$${p \over a}\sqrt {{1 \over {2\pi { \in _0}ma}}} $$
D
$${p \over a}\sqrt {{2 \over {\pi { \in _0}ma}}} $$
3
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A square loop of side 2$$a$$ and carrying current I is kept in xz plane with its centre at origin. A long wire carrying the same current I is placed parallel to z-axis and passing through point (0, b, 0), (b >> a). The magnitude of torque on the loop about z-axis will be :
A
$${{2{\mu _0}{I^2}{a^2}} \over {\pi b}}$$
B
$${{2{\mu _0}{I^2}{a^2}b} \over {\pi \left( {{a^2} + {b^2}} \right)}}$$
C
$${{{\mu _0}{I^2}{a^2}b} \over {2\pi \left( {{a^2} + {b^2}} \right)}}$$
D
$${{{\mu _0}{I^2}{a^2}} \over {2\pi b}}$$
4
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A charged particle going around in a circle can be considered to be a current loop. A particle of mass m carrying charge q is moving in a plane with speed v under the influence of magnetic field $$\overrightarrow B $$. The magnetic moment of this moving particle:
A
$${{m{v^2}\overrightarrow B } \over {2{B^2}}}$$
B
-$${{m{v^2}\overrightarrow B } \over {2{B^2}}}$$
C
-$${{m{v^2}\overrightarrow B } \over {{B^2}}}$$
D
-$${{m{v^2}\overrightarrow B } \over {2\pi {B^2}}}$$

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