PN-junction diode works as an insulator, when connected in?

In which of the three semiconducting materials listed in Table 20.1 do impurities supply free charges? (Hint: Examine the range of resistivity for each and determine whether the pure semiconductor has the higher or lower conductivity.)

A Pb wire wound in a tight solenoid of diameter of 4.0 mm is cooled to a temperature of 5.0 K. The wire is connected in series with a 50resistor and a variable source of emf. As the emf is increased, what value does it have when the superconductivity of the wire is destroyed?

Consider a power plant is located 60 km away from a residential area uses Q-gauge (A=42.40mm2) wire ofcopper to transmit power at a current of I = 100.00 A.How much more power is dissipated in the copper wires than it would be in superconducting wires?

A close analogy exists between the flow of energy by heat because of a temperature difference (see Section 19.6) and the flow of electric charge because of a potential difference. In a metal, energy dQ and electrical charge dq are both transported by free electrons. Consequently, a good electrical conductor is usually a good thermal conductor as well. Consider a thin conducting slab of thickness dx, area A, and electrical conductivity , with a potential difference dV between opposite faces. (a) Show that the current I = dq/dt is given by the equation on the left: ChargeconductionThermalconductiondqdt=A|dVdx|dQdt=kA|dTdx| In the analogous thermal conduction equation on the right (Eq. 19.17), the rate dQ/dt of energy flow by heat (in SI units of joules per second) is due to a temperature gradient dT/dx in a material of thermal conductivity k. (b) State analogous rules relating the direction of the electric current to the change in potential and relating the direction of energy flow to the change in temperature.

Show that for V less than zero, InetI0.

A valence electron in a crystal absorbs a photon of wavelength, =0.300nm . This is just enough energy to allow the electron to jump from the valence band to the conduction band. What is the size of the energy gap?

Show that the average energy of an electron in a one-dimensional metal is related to the Fermi energy by 13y31 E=12EF .

A 10-gauge copper wire has a cross-sectional area A=5.26mm2 and carries a current of I=5.00A . The adensity of copper is =89.50g/cm2 . One mole ofcopper atoms (6.021023atoms) has a mass ofapproximately 63.50 g. What is the magnitude of the drift velocity of the elections, assuming that each copper atom contributes one free electron to the current?

A tightly wound solenoid at 4.0 K is 50 cm long and is constructed from Nb wire of radius 1.5 mm. What maximum current can the solenoid carry if the wire is to remain superconducting?