1
JEE Main 2021 (Online) 24th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A soft ferromagnetic material is placed in an external magnetic field. The magnetic domains :
A
may increase or decrease in size and change its orientation.
B
increase in size but no change in orientation.
C
decrease in size and changes orientation.
D
have no relation with external magnetic field.
2
JEE Main 2021 (Online) 24th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Which of the following equations represents a travelling wave?
A
y = Aexcos($$\omega$$t $$-$$ $$\theta$$)
B
y = Ae$$-$$x2(vt + $$\theta$$)
C
y = A sin (15x $$-$$ 2t)
D
y = A sinx cos$$\omega$$t
3
JEE Main 2021 (Online) 24th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
Given below are two statements :

Statement I : PN junction diodes can be used to function as transistor, simply by connecting two diodes, back to back, which acts as the base terminal.

Statement II : In the study of transistor, the amplification factor $$\beta$$ indicates ratio of the collector current to the base current.

In the light of the above statements, choose the correct answer from the options given below.
A
Both Statement I and Statement II are false
B
Statement I is false but Statement II is true
C
Both Statement I and Statement II are true
D
Statement I is true but Statement II is false
4
JEE Main 2021 (Online) 24th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Two electrons each are fixed at a distance '2d'. A third charge proton placed at the midpoint is displaced slightly by a distance x (x << d) perpendicular to the line joining the two fixed charges. Proton will execute simple harmonic motion having angular frequency : (m = mass of charged particle)
A
$${\left( {{{2{q^2}} \over {\pi {\varepsilon _0}m{d^3}}}} \right)^{{1 \over 2}}}$$
B
$${\left( {{{{q^2}} \over {2\pi {\varepsilon _0}m{d^3}}}} \right)^{{1 \over 2}}}$$
C
$${\left( {{{2\pi {\varepsilon _0}m{d^3}} \over {{q^2}}}} \right)^{{1 \over 2}}}$$
D
$${\left( {{{\pi {\varepsilon _0}m{d^3}} \over {2{q^2}}}} \right)^{{1 \over 2}}}$$
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