NTA JEE Main 3rd September 2020 Shift 2

Concentric metallic hollow spheres of radii R and 4R hold charges $$Q_1$$ and $$Q_2$$ respectively. Given that surface charge densities of the concentric spheres are equal, the potential difference V(R) - V(4R) is:

Two resistors 400 $$\Omega$$ and 800 $$\Omega$$ are connected in series across a 6V battery. The potential difference measured by a voltmeter of 10 k$$\Omega$$ across 400 $$\Omega$$ resistor is close to:

Which of the following will NOT be observed when a multimeter (operating in resistance measuring mode) probes connected across a component, are just reversed?

A perfectly diamagnetic sphere has a small spherical cavity at its centre, which is filled with a paramagnetic substance. The whole system is placed in a uniform magnetic field $$\vec{B}$$. Then the field inside the paramagnetic substance is:

A uniform magnetic field B exists in a direction perpendicular to the plane of a square loop made of a metal wire. The wire has a diameter of 4 mm and a total length of 30 cm. The magnetic field changes with time at a steady rate dB/dt = 0.032 Ts$$^{-1}$$. The induced current in the loop is close to (Resistivity of the metal wire is 1.23 $$\times$$ 10$$^{-8}$$ $$\Omega$$m)

The electric field of a plane electromagnetic wave propagating along the x direction in vacuum is $$\vec{E} = E_0 \hat{j}\cos(\omega t - kx)$$. The magnetic field $$\vec{B}$$, at the moment t = 0 is:

Two sources of light emit X-rays of wavelength 1 nm and visible light of wavelength 500 nm, respectively. Both the sources emit light of the same power 200 W. The ratio of the number density of photons of X-rays to the number density of photons of the visible light of the given wavelengths is:

Two light waves having the same wavelength $$\lambda$$ in vacuum are in phase initially. Then the first wave travels a path $$L_1$$ through a medium of refractive index $$n_1$$ while the second wave travels a path of length $$L_2$$ through a medium of refractive index $$n_2$$. After this the phase difference between the two waves is:

The radius R of a nucleus of mass number A can be estimated by the formula $$R = (1.3 \times 10^{-15})A^{1/3}$$ m. It follows that the mass density of n nucleus is of the order of: $$(M_{prot} \cong M_{neut} \simeq 1.67 \times 10^{-27}$$ kg)

If a semiconductor photo diode can detect a photon with a maximum wavelength of 400 nm, then its band gap energy is: Planck's constant h = 6.63 $$\times$$ 10$$^{-34}$$ J.s, Speed of light c = 3 $$\times$$ 10$$^8$$ m s$$^{-1}$$