NTA JEE Main 9th January 2019 Shift 2

A power transmission line feeds input power at 2300 V to a step down transformer with its primary windings having 4000 turns. The output power is delivered at 230 V by the transformer. If the current in the primary of the transformer is 5 A and its efficiency is 90%, the output current would be:

A series AC circuit containing an inductor (20 mH), a capacitor (120 $$\mu$$F) and a resistor (60 $$\Omega$$) is driven by an AC source of 24 V/50 Hz. The energy dissipated in the circuit in 60 s is:

The energy associated with electric field is $$(U_E)$$ and with magnetic field is $$(U_B)$$ for an electromagnetic wave in free space. Then:

Two plane mirrors are inclined to each other such that a ray of light incident on the first mirror $$(M_1)$$ and parallel to the second mirror $$(M_2)$$ is finally reflected from the second mirror $$(M_2)$$ and parallel to the first mirror $$(M_1)$$. The angle between the two mirrors will be:

In a young's double slit experiment, the slits are placed 0.320 mm apart. Light of wavelength $$\lambda = 500$$ nm is incident on the slits. The total number of bright fringes that are observed in the angular range $$-30^{\circ} \leq \theta \leq 30^{\circ}$$ is:

The magnetic field associated with a light wave is given, at the origin, by $$B = B_0 [\sin(3.14 \times 10^7)ct + \sin(6.28 \times 10^7)ct]$$. If this light falls on a silver plate having a work function of 4.7 eV, what will be the maximum kinetic energy of the photoelectrons? ($$c = 3 \times 10^8$$ m s$$^{-1}$$, $$h = 6.6 \times 10^{-34}$$ J s)

At a given instant, say $$t = 0$$, two radioactive substance A and B have equal activities. The ratio $$\frac{R_B}{R_A}$$ of their activities after time $$t$$ itself decays with time $$t$$ as $$e^{-3t}$$. If the half-life of A is $$\ln 2$$, the half-life of B is:

Ge and Si diodes start conducting at 0.3 V and 0.7 V respectively. In the following figure if Ge diode connection are reversed, the value of $$V_0$$ changes by: (assume that the Ge diode has large breakdown voltage)

In a communication system operating at wavelength 800 nm, only one percent of source frequency is available as signal bandwidth. The number of channels accommodated for transmitting TV signals of band width 6 MHz are (Take velocity of light $$c = 3 \times 10^8$$ m/s, $$h = 6.6 \times 10^{-34}$$ J-s)

The pitch and the number of divisions, on the circular scale, for a given screw gauge are 0.5 mm and 100 respectively. When the screw gauge is fully tightened without any object, the zero of its circular scale lies 3 divisions below the mean line. The readings of the main scale and the circular scale, for a thin sheet, are 5.5 mm and 48 respectively, the thickness of this sheet is: