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Class12

Electric Charges and Fields

Electrostatic Potential and Capacitance

Current Electricity

Moving Charges and Magentism

Magnetism and Matter

Electromagnetic Induction

Alternating Current

Electromagnetic Waves

Ray Optics and Optical Instruments

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Dual Nature of Matter and Radiation

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Semiconductor Materials and Electronic Devices

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Experimental Skills in Physics

An electron gun with its collector at a potential of $100 \;V$ fires out electrons in a spherical bulb containing hydrogen gas at low pressure $(10^{-2}\: mm \: of\: Hg)$ A magnetic field of $2.83 \times 10^{-4} \: T$ curves the path of the electrons in a circular orbit of radius $12\; cm$ . Find e/m of the electron.

asked Dec 25, 2013 by thanvigandhi_1

1 answer

What is the de Broglie wavelength of a nitrogen molecule in air at $300\; K?$ Assume molecule is moving with the rms speed of molecules at this temp. At. mass of $N= 14.0076 \; u$

asked Dec 25, 2013 by thanvigandhi_1

1 answer

The $\lambda$ of light from the spectral emission line of sodium is $589\: nm$ . Find the $KE$ at which an electron would have the same de Broglie wavelength.

asked Dec 25, 2013 by thanvigandhi_1

1 answer

The momentum of the electrons accelerated through a potential difference of $56\; V$ is

asked Dec 25, 2013 by thanvigandhi_1

1 answer

Light of wavelength $488\: nm$ is produced by an argon laser which is used in the photoelectric effect. When light from this spectral line is incident on the emitter, the cut-off potential of photoelectrons is $0.38\: V$ . The work function of the material from which the emitter is made is

asked Dec 24, 2013 by thanvigandhi_1

1 answer

In an experiment on photoelectric effect, the slope of the cut-off voltage versus frequency of incident light is found to be $4.12 \times 10^{-15}Vs$ . Calculate the value of Planck’s constant.

asked Dec 24, 2013 by thanvigandhi_1

1 answer

Which of the following is correct?

asked Dec 24, 2013 by thanvigandhi_1

1 answer

Emission of photoelectrons from a metal plate illuminated with monochromatic electromagnetic radiation will always take place provided

asked Dec 24, 2013 by thanvigandhi_1

1 answer

A point source of light is taken away from the experimental setup of photoelectric effect, then which is the most appropriate statement?

asked Dec 24, 2013 by thanvigandhi_1

1 answer

The $KE$ of an electron with de-Broglie wavelength of $0.3\: nm$ is

asked Dec 24, 2013 by thanvigandhi_1

1 answer

Consider two light sources of wavelengths $\lambda_1\: and\: \lambda_2 (\lambda_1 > \lambda_2)$ which are emitting $n_1\: and \: n_2$ photons respectively, in a given time. Assume equal power for both sources, then

asked Dec 24, 2013 by thanvigandhi_1

1 answer

Sodium and Copper have work functions $2.3\: eV\: and \: 4.5\: eV$ respectively. Then the ratio of the wavelengths is nearest to

asked Dec 24, 2013 by thanvigandhi_1

1 answer

The work function of a substance is $4\: eV$ . The longest wavelength of light that can cause photoelectron emission from this substance is approximately

asked Dec 24, 2013 by thanvigandhi_1

1 answer

A source of light is placed at a distance $x$ from a photocell and cut off potential is $V$ . If the distance of the same source from the photocell is doubled, then cut off potential will be :

asked Dec 24, 2013 by thanvigandhi_1

1 answer

Blue light can cause photoelectric emission from a metal, but yellow light cannot. If red light is incident on the metal, then

asked Dec 24, 2013 by thanvigandhi_1

1 answer

The maximum energy of the electrons released in photocell is independent of

asked Dec 24, 2013 by thanvigandhi_1

1 answer

The energy $E$ and the momentum $p$ of photon are given by $E=hn\: and\: p=h/\lambda$ respectively. The velocity of photon will be

asked Dec 24, 2013 by thanvigandhi_1

1 answer