JEE Main 2019 Question Paper (12-Jan-2019) (Shift 2)

Question 1

Two particles $ \mathrm{A}, \mathrm{B} $ are moving on two concentric circles of radii $ R_{1} $ and $ R_{2} $ with equal angular speed $ \omega $. At $ t = 0 $, their positions and direction of motion are shown in the figure: The relative velocity $ \overrightarrow{V_{A}} - \overrightarrow{V_{B}} $ at $ t = \frac{\pi}{2 \omega} $ is given by:

Accepted Answer

$ \omega \left(R_{2} - R_{1}\right) \widehat{\mathrm{i}} $

Answer

$-\omega \left(R_{1} + R_{2}\right) \widehat{\mathrm{i}}$

Answer

$ \omega \left(R_{1} + R_{2}\right) \widehat{\mathrm{i}} $

Answer

$ \omega \left(R_{1} - R_{2}\right) \widehat{\mathrm{i}} $

Question 2

Let $L$, $R$, $C$, and $V$ represent inductance, resistance, capacitance, and voltage, respectively. The dimension of $\frac{L}{RCV}$ in $SI$ units will be:

Accepted Answer

$ \left[A^{-1}\right]$

Answer

$\left[\mathrm{LTA}\right]$

Answer

$ \left[L T^{2}\right]$

Answer

$\left[L A^{-2}\right]$

Question 3

When a certain photosensitive surface is illuminated with a monochromatic light of frequency $ \nu $, the stopping potential of the photocurrent is $ -\frac{V_0}{2} $. When the surface is illuminated by monochromatic light of frequency $ \frac{\nu}{2} $, the stopping potential is $ -V_0 $. The threshold frequency for photoelectric emission is

Accepted Answer

$\frac{3\nu}{2}$

Answer

$ \frac{5\mathrm{\nu}}{3} $

Answer

$\frac{4}{3}\nu$

Answer

$ 2
u $

Question 4

To double the covering range of a TV transmitting tower, its height should be multiplied by:

Accepted Answer

$4$

Answer

$ \frac{1}{\sqrt{2}} $

Answer

$2$

Answer

$ \sqrt{2} $

Question 5

A $10 \mathrm{m}$ long horizontal wire extends from North East to South West. It is falling with a speed of $5.0 \mathrm{m} \mathrm{s}^{-1}$, at right angles to the horizontal component of the earth's magnetic field of $0.3 	imes 10^{-4} \mathrm{Wb} \mathrm{m}^{-2}$. The value of the induced emf in the wire is:

Accepted Answer

$1.1 	imes 10^{-3}  \mathrm{V}$

Answer

$0.3 	imes 10^{-3} \mathrm{V}$

Answer

$2.5 	imes 10^{-3} \mathrm{V}$

Answer

$1.5 	imes 10^{-3} \mathrm{V}$