Question
What is the work function of metal? It depends on which factors?
✓
Answer
→Any metal has free electrons. These free electrons can move freely in the metal, hence they are responsible for the conductivity of the metal.
→However, these free electrons cannot escape from the metal surface. If an electron tries to come out of the metal, the metal surface acquires a positive charge which pulls the electron back to the metal.
→If the electron has enough energy to overcome the attraction of positive charge, it can escape from the metal.
→Thus, "The minimum energy required by an electron to escape from the metal surface is called the work function of given metal".
→It is denoted by $\phi_0$.
→The SI unit of wrok function is J. It is usually measured in eV (electron volt).
$\left(1 eV =1.6 \times 10^{-19} J\right. \text { ) }$
→$\phi_0$ depends on,
(i) type of metal
(ii) properties of metal and
(iii) type of surface.
→However, these free electrons cannot escape from the metal surface. If an electron tries to come out of the metal, the metal surface acquires a positive charge which pulls the electron back to the metal.
→If the electron has enough energy to overcome the attraction of positive charge, it can escape from the metal.
→Thus, "The minimum energy required by an electron to escape from the metal surface is called the work function of given metal".
→It is denoted by $\phi_0$.
→The SI unit of wrok function is J. It is usually measured in eV (electron volt).
$\left(1 eV =1.6 \times 10^{-19} J\right. \text { ) }$
→$\phi_0$ depends on,
(i) type of metal
(ii) properties of metal and
(iii) type of surface.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
A wire forming a loop is dipped into soap solution and taken out so that a film of soap solution is formed. A loop of 6.28cm long thread is gently put on the film and the film is pricked with a needle inside the loop. The thread loop takes the shape of a circle. Find the tension in the thread. Surface tension of soap solution = 0.030N/m.
Find the binding energy of a hydrogen atom in the state n = 2.
A block of mass m containing a net positive charge q is placed on a smooth horizontal table which terminates in a vertical wall as shown in figure. The distance of the block from the wall is d. A horizontal electric field E towards right is switched on. Assuming elastic collisions (if any) find the time period of the resulting oscillatory motion. Is it a simple harmonic motion?
Give expression for induced emf in AC generator. Discuss, with fogure, how this emf changes with time during one rotation of coil.
What is meant by polarization of light?
What is nucleus? Give a general introduction.
The masses of $^{11}C$ and $^{11}B$ are respectively 11.0114u and 11.0093u. Find the maximum energy a positron can have in the $\beta^+$-decay of $^{11}C$ to $^{11}B.$
→Answer the following question:
You have learnt that plane and convex mirrors produce virtual images of objects. Can they produce real images under some circumstances? Explain.
You have learnt that plane and convex mirrors produce virtual images of objects. Can they produce real images under some circumstances? Explain.
The speed of the yellow light in a certain liquid is $2.4 \times 10^8m/s$. Find the refractive index of the liquid.
→Define activity of a sample of a radioactive substance. The value of the disintegration constant of a radioactive substance is $0.0693h^{-1}$. Find the time after which the activity of a sample of this substance reduces to one-half that of its present value.
→