1
JEE Main 2021 (Online) 17th March Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A hairpin like shape as shown in figure is made by bending a long current carrying wire. What is the magnitude of a magnetic field at point P which lies on the centre of the semicircle?

JEE Main 2021 (Online) 17th March Evening Shift Physics - Magnetic Effect of Current Question 100 English
A
$${{{\mu _0}I} \over {4\pi r}}(2 - \pi )$$
B
$${{{\mu _0}I} \over {2\pi r}}(2 - \pi )$$
C
$${{{\mu _0}I} \over {4\pi r}}(2 + \pi )$$
D
$${{{\mu _0}I} \over {2\pi r}}(2 + \pi )$$
2
JEE Main 2021 (Online) 17th March Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A solenoid of 1000 turns per metre has a core with relative permeability 500. Insulated windings of the solenoid carry an electric current of 5A. The magnetic flux density produced by the solenoid is : (permeability of free space = 4$$\pi$$ $$\times$$ 10$$-$$7 H/m)
A
$$\pi$$T
B
2 $$\times$$ 10$$-$$3$$\pi$$ T
C
10$$-$$4$$\pi$$ T
D
$${\pi \over 5}$$ T
3
JEE Main 2021 (Online) 16th March Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A charge Q is moving $$\overrightarrow {dl} $$ distance in the magnetic field $$\overrightarrow {B} $$. Find the value of work done by $$\overrightarrow {B} $$.
A
Zero
B
$$-$$1
C
Infinite
D
1
4
JEE Main 2021 (Online) 25th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A proton, a deuteron and an $$\alpha$$ particle are moving with same momentum in a uniform magnetic field. The ratio of magnetic forces acting on them is _________ and their speed is _______, in the ratio.
A
2 : 1 : 1 and 4 : 2 : 1
B
4 : 2 : 1 and 2 : 1 : 1
C
1 : 2 : 4 and 2 : 1 : 1
D
1 : 2 : 4 and 1 : 1 : 2
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