Einstein Photoelectric Theory

Which of the following statements is correct about the photoelectric effect?

• The photoelectric effect can only occur on light sources having a high intensity.

• The photoelectric effect occurs at a certain frequency value of a light wave.

• The emitted electrons take a long time if using a dim light source.

• Electrons in the metal absorb momentum to be emitted out.

What is the function of the arrangement?

• To determine the wavelength of the Red LED.

• To determine the value of the Plank's constant

• To determine the threshold frequency

• To show the relationship between current and potential difference

The graph shows current against voltage. What is P?

• Junction voltage

• Potential difference

• Threshold frequency

• Activation voltage

Figure shows a green light with a wavelength of 550 nm irradiated on the surface of sodium metal.

Why are no electrons emitted from the surface of sodium?

• The intensity of green light is insufficient

• The frequency of green light does not exceed the threshold frequency of sodium metal

• The wavelength of the light used is too small

• The kinetic energy of electrons is insufficient

What happens to an electron when it receives energy from a photon at a threshold frequency f_o?

• Electrons are not released

• Electrons are released momentarily then reabsorbed into the metal

• Electrons are released without any kinetic energy

• Electrons only vibrate at fixed positions

Calcium, Ca has a work function, W = 2.87 eV. If a photon is irradiated on the surface of a calcium metal with frequency 7.8 x 10¹⁴ Hz, what is the maximum kinetic energy of the electrons emitted?

• 0.36 eV

• 1.25 eV

• 3.34 eV

• 6.10 eV

A ray is irradiated on the surface of a lithium metal having a work function 4.7 x 10^-19 J. If the maximum kinetic energy of the emitted electron is 3 x 10^-20 J, what is the wavelength of the ray?

• 380 nm

• 398 nm

• 420 nm

• 550 nm

Figure shows a graph for the maximum kinetic energy, K against frequency, f for the metal Potassium, K.

Based on the figure, what is the threshold wavelength for the metal Potassium, K?

• 4.84 x 10^-7 m

• 3.85 x 10^-7 m

• 5.45 x 10^-7 m

• 6.00 x 10^-7 m

Figure shows a graph for the maximum kinetic energy, K against frequency, f for the metal Cesium, Cs.

What is the velocity of a photoelectron if green monochromatic light (f = 6.5 x 10¹⁴ Hz) is irradiated on the surface of a clean Cesium, Cs metal?

• 4.23 x 10⁵ m s^-1

• 5.13 x 10⁵ m s^-1

• 5.93 x 10⁵ m s^-1

• 6.54 x 10⁵ m s^-1

Electrons are emitted from a clean nickel metal surface with a kinetic energy of 0.12 eV at 100% light intensity. What is the kinetic energy of an electron emitted if the light intensity is 50%?

• 0.12 eV

• 0.24 eV

• 0.06 eV

• 0.00 eV