Final answer:
Increasing the intensity of blue light involved in the photoelectric effect only increases the number of ejected electrons per second, not their speed or the time lag for ejection.
Step-by-step explanation:
The question pertains to the photoelectric effect, which describes that when light strikes the surface of certain metals, it can cause the emission of electrons. According to the quantum theory, this effect is related to the energy of the photons, not their intensity. However, the intensity of the light does have an effect; by increasing the intensity, more photons strike the surface, leading to a higher number of electrons being ejected — given that the frequency (color) of light is above a certain threshold value.
When the intensity of blue light is increased, the number of ejected electrons per second (B) also increases because more photons are striking the surface per unit time. The speed of the ejected electrons (A), however, remains unchanged as it depends solely on the frequency of the light (or color); higher frequency light has more energy which can be transferred to the electrons, increasing their speed. The time lag (D) between the onset of light absorption and electron ejection is also unaffected by intensity changes. Thus, the correct answer is:
B. the number of electrons ejected per second