Photo Electric Effect

If the brightness of a beam of light increases without changing its color, the ______ will increase.

• number of photons

• frequency of the light

• wavelength of the photons

• energy of the photons

In the photoelectric effect, if the incident photons have a wavelength that is larger than the threshold wavelength, _______.

• electrons will be ejected from the metal surface

• there will be photoelectric current

• no electrons will be emitted from the metal surface

• the kinetic energy of the ejected electrons increases

The energy of a photon is directly proportional to its _____ and inversely proportional to its ______.

• intensity, speed

• frequency, wavelenth

• wavelength, frequency

• intensity , wavelenth

A student has 3 lasers red, green and blue.
When the green laser is shone onto a metal surface electrons are released

• the blue laser will release more electrons

• the red laser won't release electrons

• the cut-off wavelength is shorter than the wavelength of green light.

• the blue laser will release more energetic electrons

Light of a given wavelength is used to illuminate the surface of a metal. However, no photoelectrons are emitted. In order to cause electrons to be ejected, light of __________ should be used.

• lower energy

• higher intensity

• shorter frequency

• higher frequency

Does high-frequency or low frequency light cause the ejection of a greater number of electrons from a metal surface?

• only high frequency

• only low frequency

• both high and low

• doesn't depend to frequency

What is the best description of 'threshold frequency'?

• The minimum energy needed for electrons to escape a surface.

• The maximum kinetic energy that an emitted electron has.

• The minimum frequency of a photon that will cause an electron to be emitted.

• The frequency that an emitted electron will have.

In an experiment, photoelectric effect is observed in metal A when light with frequency (f ) falls on the metal. If the light frequency used in this experiment is doubled, the photoelectrons

• Will not be ejected

• Will be ejected as observed in the previous

• Will be ejected with greater number of photoelectrons

• Will be ejected with greater kinetic energy

The maximum wavelength of radiation that can produce photo-electric effect in a certain metal is 200nm. The maximum kinetic energy acquired by electron due to radiation of wavelength 100nm will be :

• 3.21 eV

• 6.2 eV

• 12.4 eV

• 10 eV

A photocell is receiving light from a source placed at a distance of 1m. If the same source is to be placed at a distance of 2 m, then the ejected electron

• 2. will be half in number

• 1. will be one-fourth in number

• will be increased by two times

• will be decreased by two times.