Consider an n-type semiconductor with N_D = 10^{15} cm^{-3}NDâ=1015cmâ3. There is a uniform applied electric field, E = 10^5 \: V/cmE=105V/cm, throughout the semiconductor. At t = 0t=0, the semiconductor was illuminated by a sharply focused pulse of laser to create an excess hole concentration of \Delta p(t=0) = 10^{12} cm^{-3}Îp(t=0)=1012cmâ3 at x = 0x=0.Find the expression for the excess hole concentration, \Delta p(x, t)Îp(x, t), as a function of xx and tt for t > 0t>0, i. e. after the laser pulse is gone. Write your expression in terms of applied electric field, EE, generation rate GG, minority carrier lifetime, \tauÏ, diffusion coefficient, DD and mobility, \muμ. Subscript p can be omitted for simplicity.

Chapter 23, problem 075 the figure shows a geiger counter, a device used to detect ionizing radiation (radiation that causes ionization of atoms). the counter consists of a thin, positively charged central wire surrounded by a concentric, circular, conducting cylindrical shell with an equal negative charge. thus, a strong radial electric field is set up inside the shell. the shell contains a low-pressure inert gas. a particle of radiation entering the device through the shell wall ionizes a few of the gas atoms. the resulting free electrons (e) are drawn to the positive wire. however, the electric field is so intense that, between collisions with gas atoms, the free electrons gain energy sufficient to ionize these atoms also. more free electrons are thereby created, and the process is repeated until the electrons reach the wire. the resulting "avalanche" of electrons is collected by the wire, generating a signal that is used to record the passage of the original particle of radiation. suppose the radius of the central wire is 24 âµm, the inner radius of the shell 2.3 cm, and the length of the shell 14 cm. if the electric field at the shell's inner wall is 2.8 ă— 104 n/c, what is the total positive charge on the central wire?

If the wheels lock when braking suddenly the vehicle: a: loses traction b: lose steering wheel ability c: gain speed slightly d: gain steering ability

Describe uniform velocity and variable velocity in short