Question
Classify metals, conductors and semiconductors.
✓
Answer
On the basis of conductivity : On the basis of relative value of electrical conductivity $( \sigma )$ or resistivity $( \rho=$ $1 / \sigma )$ solid materials are classified as follows :
$(i)$ Metals: Their resistivity is very low $($or conductivity is very high$)$.
$\rho \sim 10^{-2}-10^{-8} \Omega m$
$\sigma \sim 10^2-10^8 Sm^{-1}$
$(ii)$ Semiconductors : Their resistivity or conductivity is between metals and insulating materials.
$\rho \sim 10^{-5}-10^6 \Omega m$
$\sigma \sim 10^5-10^{-6} Sm^{-1}$
$(iii)$ Insulators : Their resistance is very high $($or conductivity is very low$)$.
$\rho \sim 10^{11}-10^{19} \Omega m$
$\sigma \sim 10^{-11}-10^{-19} Sm^{-1}$
The values of $\rho$ and $\sigma$ given above are only indicative of the order value and may go outside the given range.
$(i)$ Metals: Their resistivity is very low $($or conductivity is very high$)$.
$\rho \sim 10^{-2}-10^{-8} \Omega m$
$\sigma \sim 10^2-10^8 Sm^{-1}$
$(ii)$ Semiconductors : Their resistivity or conductivity is between metals and insulating materials.
$\rho \sim 10^{-5}-10^6 \Omega m$
$\sigma \sim 10^5-10^{-6} Sm^{-1}$
$(iii)$ Insulators : Their resistance is very high $($or conductivity is very low$)$.
$\rho \sim 10^{11}-10^{19} \Omega m$
$\sigma \sim 10^{-11}-10^{-19} Sm^{-1}$
The values of $\rho$ and $\sigma$ given above are only indicative of the order value and may go outside the given range.
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
More "3 Marks Question" from Semiconductor Electronics: Materials, Devices and Simple Circuits→Semiconductor Electronics: Materials, Devices and Simple Circuits — all question types→Physics STD 12 Science question papers→Gujarat Board STD 12 Science question papers→Gujarat Board question paper generator→
Similar questions
The number density of free electrons in a copper conductor estimated in Example 3.1 is $8.5 \times 10^{28}m^{-3}.$ How long does an electron take to drift from one end of a wire 3.0 m long to its other end? The area of cross-section of the wire is $2.0 \times 10^{-6} m^2$ and it is carrying a current of 3.0 A.
→Figure shows a metallic rod PQ of length l, resting on the smooth horizontal rails AB positioned between the poles of a permanent magnet. The rails, the rod, and the magnetic field are in three mutually perpendicular directions. A galvanometer G connects the rails through a switch K. Assume the magnetic field to be uniform. Given the resistance of the closed-loop containing the rod is R.
i. Suppose K is open and the rod is moved with a speed v in the direction shown. Find the polarity and magnitude of induced emf.
ii. With K open and the rod moving uniformly, there is no net force on the electrons in the rod PQ even though they do experience a magnetic force due to the motion of the rod. Explain.
iii. What is the induced emf in the moving rod if the magnetic field is parallel to the rails instead of being perpendicular?
i. Suppose K is open and the rod is moved with a speed v in the direction shown. Find the polarity and magnitude of induced emf.
ii. With K open and the rod moving uniformly, there is no net force on the electrons in the rod PQ even though they do experience a magnetic force due to the motion of the rod. Explain.
iii. What is the induced emf in the moving rod if the magnetic field is parallel to the rails instead of being perpendicular?
The length of a rod is exactly 1m when measured at rest. What will be its length when it moves at a speed of:
→- $3 \times 10^5$m/s.
- $3 \times 10^6$m/s.
- $3 \times 10^7$m/s.
A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20 cm from the centre of the sphere is $1.5 \times 10^3 N/C$ and points radially inward, what is the net charge on the sphere?
→Obtain the binding energy (in MeV) of a nitrogen nucleus $(^{14}_7\text{N})$, given m $(^{14}_7\text{N})$ = 14.010307 u
→A certain sample of a radioactive material decays at the rate of 500 per second at a certain time. The count rate falls to 200 per second after 50 minutes.
- What is the decay constant of the sample?
- What is its half-life?
What is the area of the plates of a 2F parallel plate capacitor, given that the separation between the plates is 0.5 cm? [You will realise from your answer why ordinary capacitors are in the range of μF or less. However, electrolytic capacitors do have a much larger capacitance (0.1F) because of very minute separation between the conductors.]
In the given figure, voltage across the ends of inductor ( L ) and resistor ( R ) is 120 V and 90 V respectively. The root mean square value of the current is 3 A. Calculate :
(i) impedance of the circuit and (ii) phase difference between voltage and current.
(i) impedance of the circuit and (ii) phase difference between voltage and current.
When we heat an object, it expands. Is work done by the object in this process ? Is heat given to the object equal to the increase in its internal energy?
It is said that any charge given to a conductor comes to its surface. Should all the protons come to the surface? Should all the electrons come to the surface? Should all the free electrons come to the surface?