List of top Physics Questions

Eight drops of mercury of equal radii combine to form a big drop. The capacitance of a bigger drop as compared to each smaller drop is
Two thin biconvex lenses have focal lengths $f _{1}$ and $f _{2} .$ A third thin biconcave lens has focal length of $f_{3} .$ If the two biconvex lenses are in contact, the total power of the lenses is $P _{1}$. If the first convex lens is in contact with the third lens, the total power is $P _{2}$. If the second lens is in contact with the third lens, the total power is $P _{3}$ then
A slit of width 'a' is illuminated by red light of wavelength $6500 ?$. If the first diffraction minimum falls at $30 ?$, then the value of ' $a$ ' is
Which of the statements are correct with reference to single slit diffraction pattern? (i) Fringes are of unequal width (ii) Fringes are of equal width (iii) Light energy is conserved (iv) Intensities of all bright fringes are equal
In the Young's double slit experiment a monochromatic source of wavelength $\lambda$ is used. The intensity of light passing through each slit is $I _{0}$. The intensity of light reaching the screen $S _{ C }$ at a point $P$, a distance $X$ from $O$ is given by (Take $d < < D$ )
The work function of a metal is $1\, eV$. Light of wavelength $3000 \,?$ is incident on this metal surface. The velocity of emitted photoelectrons will be
A proton moving with a momentum $P _{1}$ has a kinetic energy $\frac{1}{8}$ th of its rest mass energy. Another light photon having energy equal to the kinetic energy of the possesses a momentum $P _{2} .$ Then the ratio $\frac{ P _{1}- P _{2}}{ P _{1}}$ is equal to
The size of the image of an object, which is at infinity, as formed by a convex lens of focal length $30\, cm$ is $2 \, cm .$ If a concave lens of focal length $20 \, cm$ is placed between the convex lens and the image at a distance of $26\, cm$ from the lens, the new size of the image is :
A tightly wound long solenoid has '$n$' turns per unit length, a radius ' $r$ ' and carries a current $I$. A particle having charge ' $q$ ' and mass '$m$' is projected from a point on the axis in a direction perpendicular to the axis. The maximum speed of the particle for which the particle does not strike the solenoid is
The resistance of $0.01 \,m \,KCl$ solution at $298\, K$ is $1500\, \Omega$. If the conductivity of $0.01\, m \,KCl$ solution at $298\, K$ is $0.146 \,\times \,10^{-3}\, S \,cm ^{-1} .$ The cell constant of the conductivity cell in $cm ^{-1}$ is
Suppose that the electric field amplitude of electromagnetic wave is $E _{0}=120\, NC ^{-1}$ and its frequency if $f =50 \,MHz$. Then which of the following value incorrectly computed ?
What will be the reading in the voltmeter and ammeter of the circuit shown ?
In refraction, light waves are bent on passing from one medium to second medium because, in the second medium.
A toroid with thick windings of $N$ turns has inner and outer radii $R_{1}$ and $R_{2}$ respectively. If it carries certain steady current I, the variation of the magnetic field due to the toroid with radial distance is correctly graphed in
If the refractive index from air to glass is $\frac{3}{2}$ and that from air to water is $\frac{4}{3}$, then the ratio of focal lengths of a glass lens in water and in air is
The source of electromagnetic wave can be a charge.
To propagate both longitudinal and transverse waves, a material must have
Two bodies of masses $8\, kg$ are placed at the vertices $A$ and $B$ of an equilateral triangle $A B C$. A third body of mas $2\, kg$ is placed at the centroid $G$ of the triangle. If $AG = BG = CG =1 \,m$, where should a fourth body of mass $4 \,kg$ be placed so that the resultant force on the $2\, kg$ body is zero?
In a potentiometer circuit a cell of EMF $1.5\, V$ gives balance point at $36\, cm$ length of wire. If another cell of EMF $2.5\, V$ replaces the first cell, then at what length of the wire, the balance point occurs ?
For a plane electromagnetic wave propagating in $x$-direction, which one of the following combination gives the correct possible directions for electric field (E) and magnetic field (B) respectively?
A nucleus with mass number $240$ breaks into two a fragments each of mass number $120$, the binding energy per nucleon of unfragmented nuclei is $7.6\, MeV$ while that of fragments is $8.5\, MeV$. The total gain in the Binding Energy in the process is :
A car starts from rest and accelerates at $5\, m / s ^{2}$ At $t=4\, s$, a ball is dropped out of a window by a person sitting in the car. What is the velocity and acceleration of the ball at $t =6\, s$ ? (Take $\left. g =10\, m / s ^{2}\right)$
A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since:
The electron concentration in an $n$-type semiconductor is the same as hole concentration in a $p$-type semiconductor. An external field (electric) is applied across each of them. Compare the currents in them.
An infinitely long straight conductor carries a current of $5\, A$ as shown. An electron is moving with a speed of $10^{5} m / s$ parallel to the conductor. The perpendicular distance between the electron and the conductor is $20\, cm$ at an instant. Calculate the magnitude of the force experienced by the electron at that instant.