List of top Physics Questions asked in JEE Main

According to kinetic theory of gases,
A. The motion of the gas molecules freezes at 0°C
B. The mean free path of gas molecules decreases if the density of molecules is increased.
C. The mean free path of gas molecules increases if temperature is increased keeping pressure constant.
D. Average kinetic energy per molecule per degree of freedom is \(\frac{3}{2}k_BT\) (for monoatomic gases).
Choose the most appropriate answer from the options given below:

A lead bullet penetrates into a solid object and melts. Assuming that 40% of its kinetic energy is used to heat it, the initial speed of bullet is: (Given initial temperature of the bullet = 127°C), Melting point of the bullet = 327°C, Latent heat of fusion of lead = \(2.5 × 10^4 J kg^{–1}\) Specific heat capacity of lead = 125 J/kg K)

The equation of a particle executing simple harmonic motion is given by \(x=sin\;π\bigg(t+\frac{1}{3}\bigg)m\).  At \(t = 1s\), the speed of the particle will be

Given below are two statements:
Statement I: A time varying electric field is a source of changing magnetic field and vice-versa. Thus a disturbance in electric or magnetic field creates EM waves.
Statement II: In a material medium, the EM wave travels with speed
\(V=\frac{1}{\sqrt{µ0ε0}}\) In the light of the above statements, choose the correct answer from the options given below.

If L, C and R are the self-inductance, capacitance and resistance, respectively, which of the following does not have the dimension of time?

If a charge q is placed at the centre of a closed hemispherical non-conducting surface, the total flux passing through the flat surface would be:

Three identical charged balls each of charge \(2\) \(C\) are suspended from a common point \(P\) by silk threads of \(2\) \(m\) each (as shown in figure). They form an equilateral triangle of side \(1\) \(m\). The ratio of net force on a charged ball to the force between any two charged balls will be:

A convex lens has power P. It is cut into two halves along its principal axis. Further one piece (out of the two halves) is cut into two halves perpendicular to the principal axis . Choose the incorrect option for the reported pieces.

If a wave gets refracted into a denser medium, then which of the following is true?

Given below are two statements:
Statement I: In hydrogen atom, the frequency of radiation emitted when an electron jumps from lower energy orbit \((E_1)\) to higher energy orbit \((E_2)\), is given as \(hf = E_1 – E_2.\)
Statement II: The jumping of electron from higher energy orbit \((E_2)\) to lower energy orbit \((E_1)\) is associated with frequency of radiation given as
\(f=\frac{(E_2−E_1)}{h}\) This condition is Bohr’s frequency condition.
In the light of the above statements, choose the correct answer from the options given below:

For a transistor to act as a switch, it must be operated in

We do not transmit low frequency signal to long distance because-
(a) The size of the antenna should be comparable to signal wavelength which is unreal solution for a signal of longer wavelength
(b) Effective power radiated by a long wavelength baseband signal would be high
(c) We want to avoid mixing up signals transmitted by different transmitter simultaneously
(d) Low frequency signal can be sent to long distances by superimposing with a high frequency wave as well
Therefore, the most suitable option will be

A mass of \(10\) kg is suspended vertically by a rope of length \(5\) m from the roof. A force of \(30\) N is applied at the middle point of rope in horizontal direction. The angle made by upper half of the rope with vertical is \(θ\) = \(tan^{–1} (x × 10^{–1})\). The value of \(x\) is _______.(Given, \(g = 10\; m/s^2\))

A rolling wheel of \(12\) kg is on an inclined plane at position P and connected to a mass of \(3\) kg through a string of fixed length and pulley as shown in figure. Consider PR as friction free surface.
The velocity of centre of mass of the wheel when it reaches at the bottom Q of the inclined plane PQ will be \(\frac{1}{2}\sqrt{ xgh}\) \(m/s\). The value of x is _________.

A diatomic gas\( (γ = 1.4)\) does \(400\) \(J\) of work when it is expanded isobarically. The heat given to the gas in the process is ________ \(J\).

A particle executes simple harmonic motion. Its amplitude is 8 cm and time period is 6s. The time it will take to travel from its position of maximum displacement to the point corresponding to half of its amplitude, is _________s.

A parallel plate capacitor is made up of stair like structure with a plate area A of each stair and that is connected with a wire of length b, as shown in the figure. The capacitance of the arrangement is \(\frac{x}{15} \frac{ε_0A}{b}\), the value of \(x\) is ______?

In the given circuit ‘a‘ is an arbitrary constant. The value of m for which the equivalent circuit resistance is minimum, will be \(\frac{\sqrt x}{2}\).The value of x is________.

The cut-off voltage of the diodes (shown in figure) in forward bias is \(0.6\; V\). The current through the resistor of \(40\) \(Ω\) is____ mA.

A metallic rod of length \(20\) cm is placed in North-South direction and is moved at a constant speed of 20 m/s towards East. The horizontal component of the Earth’s magnetic field at that place is \(4 × 10^{–3}\) T and the angle of dip is \(45º\). The emf induced in the rod is __________mV.

A deuteron and a proton moving with equal kinetic energy enter into a uniform magnetic field at right angle to the field. If \(r_d\) and \(r_p\) are the radii of their circular paths respectively, then the ratio \(\frac{r_d}{r_p}\) will be \(\sqrt x:1\) where \(x\) is__________

An object is thrown vertically upwards. At its maximum height, which of the following quantity becomes zero?

A ball is released from rest from point P of a smooth semi-spherical vessel as shown in figure. The ratio of the centripetal force and normal reaction on the ball at point Q is A while angular position of point Q is α with respect to point P. Which of the following graphs represent the correct relation between A and α when ball goes from Q to R?

An aluminium wire is stretched to make its length, 0.4% larger. The percentage change in resistance is