Recent questions in Physics

A laser is a coherent source because it contains:

asked Feb 25, 2014 by thanvigandhi_1

1 answer

The electromagnetic waves of frequency $2\: MHz\: to\: 30\: MHz$ are:

asked Feb 25, 2014 by thanvigandhi_1

1 answer

A gas of identical hydrogen like atoms has some atoms in lowest (ground) energy level A and some atoms in a particular upper (excited) energy , level B and there are no atoms in any other energy level . The atoms of gas make transition to higher energy level by absorbing monochromatic light photon having energy 2.7eV . Subsequently the atoms emit radiation of only six different photon energies . Some of emitted photons have energy 2.7eV some have energy more and some have less than 2.7eV . Then the principal quantum no .of initially excited level B is

asked Feb 25, 2014 by yamini.v

1 answer

The radio frequency $300\: MHz$ to $3000 \: MHz$ belong to:

asked Feb 25, 2014 by thanvigandhi_1

1 answer

An antenna is a device:

asked Feb 25, 2014 by thanvigandhi_1

1 answer

Which of the following is the disadvantage of FM over AM?

asked Feb 25, 2014 by thanvigandhi_1

1 answer

Consider the following statements \[\] Statement 1: A proton enters a strong magnetic field along the field direction. Its path and velocity remain the same\[\] Statement 2: The field exerts no force on the particle

asked Feb 25, 2014 by thanvigandhi_1

1 answer

A $\;^{118}cd\;$ radionuclide goes through transformation chain $\;^{118}Cd\; \to_{30 min}^{118}ln \to_{45 min} ^{118}Sn\;$(stable) The half lives are written below respective arrows ,A time t=0 only celuear present. Then the fraction of nuclei transformed into stable over 60 minutes:

asked Feb 25, 2014 by yamini.v

1 answer

Consider the following statements \[\] Statement 1: A magnetic field interacts with a moving charge and not with a stationary charge \[\] Statement 2: A moving charge produces a magnetic field

asked Feb 25, 2014 by thanvigandhi_1

1 answer

Consider the following statements \[\] Statement 1: The energy of a charged particle cannot change in magnetic field \[\] Statement 2: If the magnetic field does not change with time, there is no induced electric

asked Feb 25, 2014 by thanvigandhi_1

1 answer

Consider the following statements \[\] Statement 1: The energy of a charged particle does not change in spatially varying magnetic field \[\] Statement 2: The instantaneous work done by magnetic field is zero

asked Feb 25, 2014 by thanvigandhi_1

1 answer

Consider the following statements \[\] Statement 1: The energy of a charged particle in a uniform magnetic field does not change \[\] Statement 2: Magnetic field does no work

asked Feb 25, 2014 by thanvigandhi_1

1 answer

Infinitely long wires parallel to the $y$ - axis are present in the $x-y$ plane at $x = 1, x = 2, x = 4$, and so on. The currents in all the wires with odd serial no is $1A $ in the $+y$ direction while it is $1A$ in the $–y$ direction for all the wires with even serial no. The magnetic field at the origin would be

asked Feb 25, 2014 by thanvigandhi_1

1 answer

Masses of two isobars $\;_{29}^{64}Cu\;$ and $\;_{30}^{64}Zn\;$ are 63.9298n and 63.9292n respectively.It can be concluded from these data that

asked Feb 25, 2014 by yamini.v

1 answer

A straight wire of length $\ell$ carries a current $i$. The magnitude of magnetic field at the point $P$ is

asked Feb 25, 2014 by thanvigandhi_1

1 answer

A monochromatic radiation wavelength $\;\lambda_{1}\;$ is incident on a stationary atom as a result of which wavelength of photon after collision becomes $\;\lambda_{2}\;$ and recoiled atom has De- Broglie's wavelength $\;\lambda_{3}\;$.Then

asked Feb 25, 2014 by yamini.v

1 answer

The ratio of de-Broglie wavelength of moleculus of hydrogen and helium in two gas jars kept separately at temperatures $\;27^{0} C\;$ and $\;127^{0} C\;$ respectively is

asked Feb 25, 2014 by yamini.v

1 answer

The ratio of de-Broglie wavelength of a $\;\alpha\;$ particle to that of proton being subjected to same magnetic field so that the radii of their path are equal to each other assuming the field induction vector $\;\overrightarrow{B}\;$ is perpendicular to velocity vectors of $\;\alpha-\;$ particle and proton , is

asked Feb 25, 2014 by yamini.v

1 answer

If a stationary electron gets annihilated due to association with a stationary positron (hypothetically), the wavelength of resulting radiation will be .

asked Feb 25, 2014 by yamini.v

1 answer

When a metallic surface is illuminated with monochromatic light of wavelength $\;\lambda\;$ and stopping potential for photo electron current is $\;3V_{0}\;$ . When some metallic surface is illuminated with a light of wavelength $\;2 \lambda\;$ , The stopping potentials is $\;V_{0}\;$ . The threshold wavelength for surface is

asked Feb 25, 2014 by yamini.v

1 answer

A photon of wavelength $\;5030 A^{0}\;$ is incident on a totally reflecting surface. The momentum delivered by photon is equal to

asked Feb 25, 2014 by yamini.v

1 answer