The threshold wavelength for photoelectric emission from a material is $5200 \, \mathring{A}$. Photo-electrons will be emitted when this material is illuminated with monochromatic radiation from a

Light of incident frequency $2$ times the threshold frequency is incident on a photosensitive material. If the incident frequency is made $\left(\frac{1}{3}\right)^{\text{rd}}$ and intensity is doubled,then the photoelectric current will

$A$ copper ball of radius $1\, cm$ and work function $4.47\, eV$ is irradiated with ultraviolet radiation of wavelength $2500\, \mathring{A}$. The effect of irradiation results in the emission of electrons from the ball. Further,the ball will acquire charge,and due to this,there will be a finite value of the potential on the ball. The charge acquired by the ball is:

The work function of a substance is $3.0 \ eV$. The longest wavelength of light that can cause the emission of photoelectrons from this substance is approximately: (in $nm$)

The maximum velocity of electrons emitted from a metal surface is $V$,when the frequency of light falling on it is $f$. What is the maximum velocity when the frequency becomes $4f$?

If in an experiment of photoelectric effect,the wavelength of light is decreased by $60\%$,then $K_{max}$ changes from $5\,eV$ to $17\,eV$. The work function of the metal is ............. $eV$.