NTA JEE Main 24th February 2021 Shift 1

In the given figure, a mass $$M$$ is attached to a horizontal spring which is fixed on one side to a rigid support. The spring constant of the spring is $$k$$. The mass oscillates on a frictionless surface with time period $$T$$ and amplitude $$A$$. When the mass is in equilibrium position, as shown in the figure, another mass $$m$$ is gently fixed upon it. The new amplitude of oscillation will be:

A cube of side $$a$$ has point charges +Q located at each of its vertices except at the origin where the charge is -Q. The electric field at the centre of cube is: 

Two equal capacitors are first connected in series and then in parallel. The ratio of the equivalent capacities in the two cases will be:

A current through a wire depends on time as $$i = \alpha_0 t + \beta t^2$$, where $$\alpha_0 = 20$$ A s$$^{-1}$$ and $$\beta = 8$$ A s$$^{-2}$$. Find the charge crossed through a section of the wire in 15 s.

A cell $$E_1$$ of emf 6 V and internal resistance 2$$\Omega$$ is connected with another cell $$E_2$$ of emf 4 V and internal resistance 8 $$\Omega$$ (as shown in the figure). The potential difference across points X and Y is:

The focal length $$f$$ is related to the radius of curvature $$r$$ of the spherical convex mirror by:

In a Young's double slit experiment, the width of the one of the slit is three times the other slit. The amplitude of the light coming from a slit is proportional to the slit-width. Find the ratio of the maximum to the minimum intensity in the interference pattern.

Given below are two statements:
Statement I: Two photons having equal linear momenta have equal wavelengths.
Statement II: If the wavelength of the photon is decreased, then the momentum and energy of a photon will also decrease.
In the light of the above statements, choose the correct answer from the options given below.

In the given figure, the energy levels of hydrogen atom have been shown along with some transitions marked A, B, C, D and E. The transitions A, B and C respectively represent

If an emitter current is changed by 4 mA, the collector current changes by 3.5 mA. The value of $$\beta$$ will be: