JEE Main 2021 Question Paper (24-Feb-2021) (Shift 2)

Question 1

The period of oscillation of a simple pendulum is $ T = 2\pi \sqrt{\frac{L}{g}} $. The measured value of $ L $ is $ 1.0  \mathrm{m} $ from a meter scale having a minimum division of $ 1\mathrm{mm} $, and the time of one complete oscillation is $ 1.95  \mathrm{s} $ measured from a stopwatch with a resolution of $ 0.01  \mathrm{s} $. The percentage error in the determination of $ g $ will be:

Accepted Answer

$1.13\%$

Answer

$1.03\%$

Answer

$1.33\%$

Answer

$1.30\%$

Question 2

On the basis of kinetic theory of gases, the gas exerts pressure because its molecules:

Accepted Answer

suffer change in momentum when impinging on the walls of the container.

Answer

Continuously stick to the walls of the container.

Answer

Continuously lose their energy till it reaches the wall.

Answer

are attracted by the walls of the container.

Question 3

The logic circuit shown above is equivalent to :

Accepted Answer

""

Answer

Answer

Answer

Question 4

The de Broglie wavelength of a proton and $\alpha$-particle are equal. The ratio of their velocities is

Accepted Answer

$4:1$

Answer

$4:3$

Answer

$1:4$

Answer

$4:2$

Question 5

An X-ray tube is operated at $1.24$ million volts. The shortest wavelength of the produced photon will be:

Accepted Answer

$10^{-3} \mathrm{nm}$

Answer

$10^{-2} \mathrm{nm}$

Answer

$10^{-4} \mathrm{nm}$

Answer

${10}^{-1}\,\mathrm{nm}$