NTA JEE Main 10th April 2019 Shift 2

A square loop is carrying a steady current I and the magnitude of its magnetic dipole moment is m. If this square loop is changed to a circular loop and it carries the same current, the magnitude of the magnetic dipole moment of circular loop will be:

The magnitude of the magnetic field at the centre of an equilateral triangular loop of side 1 m which is carrying a current of 10 A is:
[Take $$\mu_0 = 4\pi \times 10^{-7}$$ N A$$^{-2}$$]

A coil of self inductance 10 mH and resistance of 0.1 Ω is connected through a switch to a battery of internal resistance 0.9 Ω. After the switch is closed, the time taken for the current to attain 80% of the saturation value is: [ln5 = 1.6]

The graph shows how the magnification m produced by a thin lens varies with image distance v. The focal length of the lens used is

In a Young's double-slit experiment, the ratio of the slit's width is 4:1. The ratio of the intensity of maxima to minima, close to the central fringe on the screen, will be

Light is incident normally on a completely absorbing surface with an energy flux of 25 W cm$$^{-2}$$. If the surface has an area of 25 cm$$^2$$, the momentum transferred to the surface in 40 min time duration will be:

A 2 mW laser operates at a wavelength of 500 nm. The number of photons that will be emitted per second is:
[Given Planck's constant h = $$6.6 \times 10^{-34}$$ J s, speed of light c = $$3.0 \times 10^8$$ m/s]

In Li$$^{++}$$, electron in first Bohr orbit is excited to a level by a radiation of wavelength $$\lambda$$. When the ion gets de-excited to the ground state in all possible ways (including intermediate emissions), a total of six spectral lines are observed. What is the value of $$\lambda$$?
(Given: h = $$6.63 \times 10^{-34}$$ J s; c = $$3 \times 10^8$$ m s$$^{-1}$$)

Two radioactive substances A and B have decay constants $$5\lambda$$ and $$\lambda$$ respectively. At t = 0, a sample has the same number of the two nuclei. The time taken for the ratio of the number of nuclei to become $$\frac{1}{e^2}$$ will be

The figure represents a voltage regulator circuit using a Zener diode. The breakdown voltage of the Zener diode is 6 V and the load resistance is, R$$_L$$ = 4 kΩ. The series resistance of the circuit is R$$_i$$ = 1 kΩ. If the battery voltage V$$_B$$ varies from 8 V to 16 V, what are the minimum and maximum values of the current through Zener diode?