List of top Physics Questions

Electromagnetic waves were first of all produced in the laboratory by

The wavelength of electromagnetic waves produced by Hertz was about

The ratio of kinetic energy and the total energy of the electron in the $n^{th}$ quantum state of Bohr's atomic model of a hydrogen atom is

An electric charge in uniform motion produces

Electromagnetic waves are

Which among the following does not represent Maxwell's equation?

If $\mu_{0}$ be the permeability and $\varepsilon_{0}$ be the permittivity of a medium, then its refractive index is given by

The requirement of transmitting microwaves from one position to another on the earth is that

How many geo-synchronous satellites are required to provide the communication over the whole part of the earth

In optical fibre communication system, light source can be

Filters are essential components to

Light emerging from the end of an optical fibre link must be detected and converted into electronic pulses for further processing so that

The height if geo-synchronous orbit from the surface of the earth is

Analog signal can be converted into digital signal and vice-versa with the help of a device called

A $10\, kW$ drilling machine is used to drill a bore in a small aluminium block of mass $8 \,kg$. Find the rise in temperature of the block in $2.5$ minutes, assuming $50\%$ power is used up in heating the machine itself or lost to the surroundings. (Specific heat of aluminium $= 0.91\, J \,g^{-1} \,^{\circ}C^{-1}$)

The $B-H$ curve for a ferromagnet is shown in the figure. The ferromagnet is placed inside a long solenoid with $1000 \, turns \, cm^{- 1}$ . The current that should be passed in the solenoid to demagnetise the ferromagnet completely is

The magnetic field at the point of intersection of diagonals of a square loop of side $L$ carrying a current $I$ is

Mixed $He^{+}$ and $O^{2 +}$ ions (mass of $H e^{+}=4 \, amu \, and \, that \, of \, O^{2 +}=16 \, amu$ ) beam passes a region of constant perpendicular magnetic field. If kinetic energy of all the ions is same, then

A current $I$ flows along the length of an infinitely long, straight, thin-walled pipe. Then

A $1\, kg$ block situated on a rough incline is connected to a spring of negligible mass having spring constant $100\, N\,m^{-1}$ as shown in the figure.

The block is released from rest with the spring in the unstretched position. The block moves $10\, cm$ down the incline before coming to rest. The coefficient of friction between the block and the incline is (Take $g = 10\, ms^{-2}$ and assume that the pulley is frictionless)

A 1.0 mH inductance, a 10 $\mu F$ capacitance and a 5.0 ohm resistance are connected in series to an a.c. source. It is found that the inductor and the capacitor show equal reactances. The reactance should be nearest to

A $0.5\, kg$ ball is thrown vertically up with $14 \,m s^{-1}$. It attains a height of $8\,m$. The energy dissipated by air drag acting on the ball during ascent is

A $0.2\, k\Omega$ resistor and $15\,\mu F$ capacitor are connected in series to a $220\,V$, $50\,Hz$ ac source. The impedance of the circuit is

$^{}_{92}U^{238}$ on absorbing a neutron goes over to $^{}_{92}U^{239} .$ This nucleus emits an electron to go over to neptunium which on further emitting an electron goes over to plutonium. The resulting plutonium can be expressed as.

Clouds appear to float in air due to