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
Two loudspeakers are arranged facing each other at some distance. Will a person standing behind one of the loudspeakers clearly hear the sound of the other loudspeaker or the clarity will be seriously damaged because of the 'collision' of the two sounds in between?
A sample of $0.177g$ of an ideal gas occupies $1000\ cm^3$ at $\text{STP}.$ Calculate the $\text{rms}$ speed of the gas molecules.
→Figure shows a long U-shaped wire of width l placed in a perpendicular magnetic field B. A wire of length l is slid on the U-shaped wire with a constant velocity v towards right. The resistance of all the wires is r per unit length. At t = 0, the sliding wire is close to the left edge of the U-shaped wire. Draw an equivalent circuit diagram, showing the induced emf as a battery. Calculate the current in the circuit.
A circular coil of radius 2.0cm has 500 turns and carries a current of 1.0A. Its axis makes an angle of 30° with the uniform magnetic field of magnitude 0.40 T that exists in the space. Find the torque acting on the coil.
Show that the slope of p-V diagram is greater for an adiabatic process as compared to an isothermal process.
Explain electric field produced by the point electric charge.
Explain conductors and insulators with example. (This question can also be asked as difference between conductors and insulators.)
Draw a labelled ray diagram to show the image formation in a refracting type astronomical telescope. Why should the diameter of the objective of a telescope be large?
A convex lens of focal length $f_1$ is kept in contact with a concave lens of focal length $f_2.$ Find the focal length of the combination.
→A dbuteron and an alpha particle are accelerated with the same accelerating potential. Which one of the two has:
- Greater value of de-Broglie wavelength, associated with it and
- Less kinetic energy? Explain.