1 Physics -- Photons

Define work function.Describe the result obtained in experiments to investigate the variation of photoelectric emission as the intensity and the frequency of the incident light are varied. If the wavelength of the incident light is reduced from 400 nm to 360 nm, there is a change in the...

Define work function.Describe the result obtained in experiments to investigate the variation of photoelectric emission as the intensity and the frequency of the incident light are varied. If the wavelength of the incident light is reduced from 400 nm to 360 nm, there is a change in the stopping potential of 0.34 V. Find the value Planck's constant.

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The minimum amount of energy necessary to start the emission of electrons from a metal's surface is known as its work function.

Intensity of Light: If a high intense light of frequency equal or greater than threshold frequency falls on the surface of matter, the photoelectric effect is caused. Since studying the impact of this factor is the focus of this research study, therefore, it would be discussed in detail however: one thing which is very clear is that the emission of electrons does not depend upon the intensity of light unless the frequency of light is greater than the threshold frequency.

Frequency: If a beam of light with frequency equal to or greater than threshold frequency strikes the surface of matter, photoelectric effect is produced. If frequency is less than the threshold frequency, then photoelectric effect cannot be seen. The threshold frequency varies from matter to matter.

Given :

λ₁ = 400nm = 400 * 10^-9 m

λ₀ = 360nm = 360 *10^-9 m

V_s = 0.34 V

e = 1.6 * 10 ^-19 C

c = 3 * 10 ⁸ m/s

we have ,

e V_s = hf₁ - hf₀

e V_s = (hc / λ₁ ) - (hc / λ₀)

e V_s /hc = (1/λ₁) - (1/λ₀)

(1.6 * 10 ^-19 * 0.34 ) * h . 3 * 10 ⁸ =( 1 / 400 * 10^-9) - (1 / 360 *10^-9 )

1/h = 1.5 * 10 ³³

h = 6.66 * 10 ³⁴ Js

Hence , the value Planck's constant is 6.66 * 10 ³⁴ Js .

Write the truth table of the OR gate and the NAND gate. How the OR gate is drawn by using the NAND gate?

Considering, 1 as high input/output and 0 as low input/output

OR Gate (Truth Table)

First Input(A)	Second Input(B)	Output(Y)
1	1	1
1	0	1
0	1	1
0	0	0

NAND Gate (Truth Table)

First Input(A)	Second Input(B)	A.B(AND output)	NAND Output(Y)
1	1	1	0
0	1	0	1
0	0	0	1
1	0	0	1

As shown in the above figure, three NAND gates are connected such that the output of first two NAND gates are connected as inputs of the third NAND gate. The inputs for first two gates...

Which of the following statements are true for the fact :Depletion layer is called "depletion layer ". A. It is depleted of charge carrier density B. It is depleted of charge densityC. It has barri...

The answer is A

In the depletion layer, electrons combine with holes producing charge density so that region is depleted of charge carriers but it has charge density .

Conclusion: Neutral but still having non zero charge density .

Why do holes have effective mass although being vacant energy states ?

Hi Sushin,

In solid state physics, a particle'seffective mass(often denoted $\text{[math]}$ ) is themassthat itseemsto have when responding to forces. Here, although we define and understand holes as vacancies, when they "move" towards the positive terminal under the electrical field, the concept of effective mass is introduced.

Hope this helps.

The input junction of transistor is always forward biased and output junction is reversed biases Why? Explain.

What is proper biasing?

A transistor is said to be properly biased when emitter junction is forward biased and collector junction is reverse biased.

Why are alkali metals most suited for photoelectric emissions?

Since the atom of alkali metal has only one valence electron, it is lightly bound with the nucleus so that the work function of alkali metal is less than that of the other metal. So the photoelectrons are easily emitted from the surface of alkali metal with visible light. On the other hand, metals such as zinc, cadmium etc. require high energy radiation (UV light) to emit photoelectrons.

Describe Millikan's experiment to determine the value of Planck's constant h .

Explain why there are no photoelectrons emitted when the frequency of the incident light is less than 5.6 x 10¹⁴ Hz.(i) Calculate the work function for sodium. (ii)Use the graph to calculate the va...

When the frequency of the incident light is less than 5.6 x 10 Hz, no photoelectrons are emitted because the energy of the incident photons is less than the work function of sodium, and hence the electrons do not have enough energy to overcome the work function and be emitted.

(i) We can calculate the work function of sodium using the equation:

Energy of incident photon = work function + maximum kinetic energy of photoelectrons

At the threshold frequency, the maximum kinetic energy of...

Explain what is meant by photoelectric effect. Explain how the photoelectric effect gives evidence for this phenomenon. Figure shows the maximum kinetic energy of the emitted photoelectrons as th...

photoelectric effect is aphenomenon in which electrically charged particles are released from or within a material when it absorbs electromagnetic radiation.

The photoelectric effect provides evidence for the particle-like nature of light because the effect can only be explained by treating light as a collection of particles, or photons, that carry energy. It also supports the idea of quantized energy levels in atoms, where only specific photon energies can excite electrons to higher energy...

Explain why photoelectric effect cannot be observed with all wave lengths of light ?

The amount of energy required to eject an electron just out of the surface of metal is called work function of metal. The frequency of the light required for this purpose is called threshold frequency f0. Then we have

Φ = h f₀= hc /λ₀whereλ₀=threesold wavelength = wave length

corresponding to threshold frequency.It is clear that a frequency less than f₀ (i.e. wavelength greater than A) will be unable to produce the photo electric effect. This is the reason why photoelectric effect cannot be...

Which has more energy, a photo in the infrared or one in the ultraviolet?

What determines the maximum velocity of photoelectrons?

The frequency of incident radiation and work function of the metal determine the maximum velocity of photoelectrons.