# Chapter 15 : Electric Properties¶

### Example 15.1 pageno : 391¶

In :
# Variables
v = 230.;			#in volts
d = 0.005;			#in m

# Calculations
E = -v/d;			#in V/m

# Results
print "Electric field between pair of conducting plates (in V/m)  =  ",E

Electric field between pair of conducting plates (in V/m)  =   -46000.0


### Example 15.2 pageno : 391¶

In :
# Variables
n = 10.**19;			#no. of electrons per unit volume
e = 1.602*10**-19;			#charge of an electron in C
a = 0.018;			#conductivity in ohm/m
m = 9.1*10**-31;			#mass of an electron in kg
v = 0.16;			#in volts
t = 0.29;			#thickness in mm

# Calculations
efg = v/t;			#electric field gradient in V/m
vd = a*efg/(n*e);
vd1 = 10**3*vd;			#in m/s

# Results
print "Drift Velocity (in m/sec)  =  %.3f m/s"%vd1

Drift Velocity (in m/sec)  =  6.199 m/s


### Example 15.3 pageno : 399¶

In :
# Variables
l = 200.;   	    		#in m
r = 21.;	    	    	#in ohm
d = 0.44*10**-3;			#in m

# Calculations
a = 3.14*(d/2)**2;			#area in sq m
p = r*a/l;			#in ohm-m

# Results
print "Specific Resistance (in ohm-m)  =  %.3e ohm-m"%p

Specific Resistance (in ohm-m)  =  1.596e-08 ohm-m


### Example 15.4 pageno : 400¶

In :
# Variables
p_cu = 0.015*10**-6;			#resistivity of copper in ohm-m
p_ni = 0.012*10**-6;			#resistivity of nickel in ohm-m
p_ag = 0.016*10**-6;			#resistivity of silver in ohm-m
c1 = 0.25;			#atomic % of nickel
c2 = 0.4;			#atomic % of silver

# Calculations
p = p_cu+(c1*p_ni)+(c2*p_ag);

# Results
print "Resistivity of Cu-Ni-Ag alloy at 300 K (in ohm-m)  =  %.2e ohm m"%p

Resistivity of Cu-Ni-Ag alloy at 300 K (in ohm-m)  =  2.44e-08 ohm m


### Example 15.5 pageno : 407¶

In :
# Variables
m = 0.14;			#mobility of electron
u_h = 0.05;			#mobility of holes
p = 3000.;			#resistivity in ohm-m

# Calculations
e = 1.602*10**-19;			#charge of an electron in C
a = 1./p;			#conductivity
n = a/(e*(m+u_h));

# Results
print "Intrinsic Carrier density in pure silicon (in per cu m)  =  %.3e m**3"%n

Intrinsic Carrier density in pure silicon (in per cu m)  =  1.095e+16 m**3


### Example 15.6 pageno : 410¶

In :
# Variables
id = 1000.;			#in A/sqm
p = 0.05;			#resistivity in ohm-m
l = 100.*10**-6;			#in m
m_e = 0.4;			#in sqm/Vsec
e = 1.602*10**-19;			#charge of electron in C

# Calculations
a = 1./p;			#conductivity
n_e = a/(e*m_e);			#in per cubic m
v_d = id/(n_e*e);			#in m/s
t = l/v_d;			#in sec
t1 = t*10**6;			#in msec

# Results
print "Drift Velocity (in m/s)  =  %.f m/s"%v_d
print "Time taken by electrons (in msec)  =  %.f ms"%t1

Drift Velocity (in m/s)  =  20 m/s
Time taken by electrons (in msec)  =  5 ms


### Example 15.7 pageno : 410¶

In :
# Variables
d = 1.*10**-3;	    		#diameter in m
a = 3.14*(d/2)**2;			#area of cross section of rod in sq m
r = 100.;			        #in ohm

# Calculations
l = 10.*10**-3;			    #in m
p = a*r/l;			        #in ohm-m
c = 1./p;	        		#conductivity
e = 1.602*10**-19;			#charge of electron in C
u_h = 0.19;			        #mobility of holes in sqm/Vsec
n_h = c/(e*u_h);

# Results
print "Impurity concentration in rod (in per cubic m)  =  %.2e m**3"%n_h

Impurity concentration in rod (in per cubic m)  =  4.19e+21 m**3


### Example 15.8 pageno : 413¶

In :
# Variables
ni = 1.5*10**16;			#intrinsic carrier concentration per cu. m
n = 10**19;			#no. of conduction electrons in per cu. m

# Calculations
p = ni**2/n;			#in per cu.m

# Results
print "Conduction electron and hole density (per cubic m)  =  %.2e m**3"%p

Conduction electron and hole density (per cubic m)  =  2.25e+13 m**3


### Example 15.9 pageno : 413¶

In :
import math

# Variables
nd = 10.**17;			#in per cu cm
ni = 1.5*10**10;			#in cu cm
t = 300;			#in K

# Calculations
ne = nd;			#nd>>ni
nh = ni**2/ne;
e = 0.0259*math.log(ne/ni);			#in eV

# Results
print "Hole concentration (in per cubic cm)  =  %.2e /cm**3"%nh
print "Location of Fermi Level (in eV)  =  %.3f eV"%e

Hole concentration (in per cubic cm)  =  2.25e+03 /cm**3
Location of Fermi Level (in eV)  =  0.407 eV


### Example 15.10 pageno : 423¶

In :
# Variables
d = 40000.;			    #dielectric strength in V/mm
v = 33*10.**3;			#in volts

# Calculations
t = v/d;			#in mm

# Results
print "thickness of insulation (in mm)  =  %.3f m m"%t

thickness of insulation (in mm)  =  0.825 m m


### Example 15.14 page no : 424¶

In :
# Calculation

T = 0.0464*10**5/2.9444

# Result
print "Temperature T = %.1f K"%T

Temperature T = 1575.9 K


### Example 15.16 pageno : 425¶

In :
# Variables
c = 2.99*10**8;		    	#speed of light in m/s
h = 6.62*10**-24;			#planck's constant
l = 1.771*10**-6             #wavelength in m

# Calculations
eg = (h*c)/l;	        		#in J

# Results
print "Band gap energy (in J)  =  %.2e Joules"%eg

Band gap energy (in J)  =  1.12e-09 Joules