List of top Physics Questions asked in JEE Main

A small object at rest, absorbs a light pulse of power $20 \,mW$ and duration $300\, ns$. Assuming speed of light as $3 \times 10^8 \,m / s$, the momentum of the object becomes equal to :

As per given figure, a weightless pulley $P$ is attached on a double inclined frictionless surfaces. The tension in the string (massless) will be (if $g =10 \,/ s ^2$ )

As per the given figure, a small ball $P$ slides down the quadrant of a circle and hits the other ball $Q$ of equal mass which is initially at rest Neglecting the effect of friction and assume the collision to be elastic, the velocity of ball $Q$ after collision will be :$\left( g =10 \,m / s ^2\right)$

The radius of electron's second stationary orbit in Bohr's atom is $R$ The radius of 3rd orbit will be

Match List I with List II

LIST I		LIST II
A	Surface tension	1	kgm⁻¹s⁻¹
B	Pressure	2	kgms⁻¹
C	Viscosity	3	kgm⁻¹s⁻²
D	Impulse	4	kgs⁻²

Choose the correct answer from the options given below:

Two isolated metallic solid spheres of radii $R$ and $2 R$ are charged such that both have same charge density $\sigma$. The spheres are then connected by a thin conducting wire. If the new charge density of the bigger sphere is $\sigma^{\prime}$ The ratio $\frac{\sigma^{\prime}}{\sigma}$ is :

Two objects $A$ and $B$are placed at $15\, cm$ and $25\, cm$ from the pole in front of a concave mirros having radius of curvature $40\, cm$. The distance between images formed by the mirror is:

A single turn current loop in the shape of a right angle triangle with sides 5cm, 12cm, 13cm is carrying a current of 2A. The loop is in a uniform magnetic field of magnitude 0.75T whose direction is parallel to the current in the 13 cm side of the loop. The magnitude of the magnetic force on the 5 cm side will be $\frac{x}{130} N$. The value of x is ________ .

A stream of a positively charged particles having $\frac{q}{ m }=2 \times 10^{11} \frac{ C }{ kg }$ and velocity $\vec{v}_0=3 \times 10^7 \hat{i} m / s$ is deflected by an electric field $18 kV / m$ The electric field exists in a region of $10 cm$ along $x$ direction Due to the electric field, the deflection of the charge particles in the $y$ direction is___ $mm$

As shown in the figure, a combination of a thin plano concave lens and a thin plano convex lens is used to image an object placed at infinity The radius of curvature of both the lenses is $30 \,cm$ and refraction index of the material for both the lenses is $175$ Both the lenses are placed at distance of $40 \,cm$ from each other Due to the combination, the image of the object is formed at distance $x=$__ $cm$, from concave lens.

In a potentiometer arrangement, a cell of emf $1.20\, V$ gives a balance point at $36 \, cm$ length of wire This cell is now replaced by another cell of emf $1.80\, V$. The difference in balancing length of potentiometer wire in above conditions will be _______$cm$

Magnetic flux (in weber) in a closed circuit of resistance $20 \,\Omega$ varies with time $t ( s )$ as $\phi=8 t^2-9 t+5$. The magnitude of the induced current at $t =0.25\, s$ will be ______$mA$

A convex lens of refractive index $15$ and focal length$18 \,cm$ in air is immersed in water. The change in focal length of the lens will be_______ cm (Given refractive index of water =$\frac{4}{3}$)

A convex lens of focal length $20\, cm$ is placed in front of convex mirror with principal axis coinciding each other The distance between the lens and mirror is $10\, cm$ A point object is placed on principal axis at a distance of $60 \, cm$ from the convex lens The image formed by combination coincides the object itself The focal length of the convex mirror is ________ $cm$

Assume that protons and neutrons have equal masses Mass of a mucleon is $16 \times 10^{-27} kg$ and radius of nucleus is $15 \times 10^{-15} A ^{1 / 3} m$ The approximate ratio of the nuclear density and water density is $n \times 10^{13}$ The value of $n$ is ___