Chapter 2: An Introduction to Electric Circuits

Example 1, page no. 12

In [1]:
from __future__ import division
#initializing the variables:
Q = 0.24; # in Coulomb
t = 0.015; # in sec

#calculation:
I = Q/t

#results
print "Current(I):", I,"Ampere(A)"

Current(I): 16.0 Ampere(A)

Example 2, page no. 12

In [2]:
from __future__ import division
#initializing the variables:
I = 10; # in Ampere
t = 240; # in sec

#calculation:
Q = I*t

#resuts
print "Charge(Q):", Q,"Coulomb(C)"

Charge(Q): 2400 Coulomb(C)

Example 3, page no. 14

In [3]:
from __future__ import division
#initializing the variables:
I = 0.8; # in Ampere
V = 20; # in Volts

#calculation:
R = V/I

#results
print "Resistance(R):", R,"Ohms"

Resistance(R): 25.0 Ohms

Example 4, page no. 15/h3>

In [4]:
from __future__ import division
#initializing the variables:
I = 0.010; # in Ampere
R = 2000; # in ohms

#calculation:
V = I*R

#results
print "p.d.(V):", V,"Volts(V)"

p.d.(V): 20.0 Volts(V)

Example 5, page no. 15/h3>

In [5]:
from __future__ import division
#initializing the variables:
I = 0.050; # in Ampere
V = 12; # in Volts

#calculation:
R = V/I

#results
print "Resistance(R):", R,"Ohms"

Resistance(R): 240.0 Ohms

Example 6, page no. 15/h3>

In [6]:
from __future__ import division
#initializing the variables:
I1 = 0.005; # in Ampere
V1 = 100; # in Volts
V2 = 25; # in Volts

#calculation:
R = V1/I1
I2 = V2/R

#results
print "Resistance(R):", R,"Ohms"
print "Current(I):", I2,"Ampere(A)"

Resistance(R): 20000.0 Ohms
Current(I): 0.00125 Ampere(A)

Example 7, page no. 15/h3>

In [7]:
from __future__ import division
#initializing the variables:
I1 = 0.050; # in Ampere
I2 = 200E-6; # in Ampere
V = 120; # in Volts

#calculation:
R1 = V/I1
R2 = V/I2

#results
print "Resistance(R1):", R1,"Ohms"
print "Resistance(R2):", R2,"Ohms"

Resistance(R1): 2400.0 Ohms
Resistance(R2): 600000.0 Ohms

Example 8, page no. 16

In [8]:
from __future__ import division
#initializing the variables:
P = 100; # in Watt
V = 250; # in Volts

#calculation:
I = P/V
R = V/I

#results
print "Current(I):", I,"Ampere(A)"
print "Resistance(R):", R,"Ohms"

Current(I): 0.4 Ampere(A)
Resistance(R): 625.0 Ohms

Example 9, page no. 17

In [9]:
from __future__ import division
#initializing the variables:
I = 0.004; # in ampere
R = 5000; # in ohms

#calculation:
P = I*I*R

#results
print "Power(P):", P,"Watt(W)"

Power(P): 0.08 Watt(W)

Example 10, page no. 17

In [10]:
#Find also the power rating of the kettle.
from __future__ import division
#initializing the variables:
V = 240; # in Volts
R = 30; # in ohms

#calculation:
I = V/R
P = V*I

#results
print "Current(I):", I,"Ampere(A)"
print "Power(P):", P,"Watt(W)"

Current(I): 8.0 Ampere(A)
Power(P): 1920.0 Watt(W)

Example 11, page no. 17

In [11]:
from __future__ import division
#initializing the variables:
I = 5; # in ampere
R = 100; # in ohms

#calculation:
V = I*R
P = I*R*I

#results
print "p.d(V):", V,"Volts(V)"
print "Power(P):", P,"Watt(W)"

p.d(V): 500 Volts(V)
Power(P): 2500 Watt(W)

Example 12, page no. 17

In [12]:
from __future__ import division
#initializing the variables:
I1 = 0.020; # in ampere
V1 = 20; # in Volts
I2 = 0.005; # in ampere
V2 = 16; # in Volts

#calculation:
R1 = V1/I1
R2 = V2/I2

#results
print "Resistance(R1):", R1,"Ohms"
print "Resistance(R2):", R2,"Ohms"

Resistance(R1): 1000.0 Ohms
Resistance(R2): 3200.0 Ohms

Example 13, page no. 18

In [14]:
from __future__ import division
#initializing the variables:
V = 240; # in Volts
R = 960; # in ohms

#calculation:
I = V/R
P = I*V

#results
print "Current(I):", I,"Ampere(A)"
print "Power(P):", P,"Watt(W)"

Current(I): 0.25 Ampere(A)
Power(P): 60.0 Watt(W)

Example 14, page no. 18

In [15]:
from __future__ import division
#initializing the variables:
V = 12; # in Volts
R = 40; # in ohms
t = 120; # in sec

#calculation:
I = V/R
P = I*V
E = P*t

#results
print "Current(I):", I,"Ampere(A)"
print "Power(P):", P,"Watt(W)"
print "Energy(E):", E,"Joule(J)"

Current(I): 0.3 Ampere(A)
Power(P): 3.6 Watt(W)
Energy(E): 432.0 Joule(J)

Example 15, page no. 18

In [16]:
from __future__ import division
#initializing the variables:
V = 15; # in Volts
I = 2; # in ampere
t = 360; # in sec

#calculation:
E = V*I*t

#results
print "Energy(E):", E,"Joule(J)"

Energy(E): 10800 Joule(J)

Example 16, page no. 18

In [17]:
from __future__ import division
#initializing the variables:
V = 240; # in Volts
I = 13; # in ampere
t = 30; # in hours
p = 7; # in paise per kWh

#calculation:
P = V*I
E = P*t/1000 # in kWh
C = E*p

#results
print "Cost per week:", C," Paise(p)"

Cost per week: 655.2  Paise(p)

Example 17, page no. 19

In [18]:
from __future__ import division
#initializing the variables:
V = 250; # in Volts
E = 3.6E6; # energy in J
t = 2400; # in sec

#calculation:
P = E/t
I = P/V

#results
print "Power(P):", P,"Watt(W)"
print "Current(I):", I,"Ampere(A)"

Power(P): 1500.0 Watt(W)
Current(I): 6.0 Ampere(A)

Example 18, page no. 19

In [18]:
from __future__ import division
#initializing the variables:
R = 20; # in ohms
I = 10; # in ampere
t = 6; # in hours
p = 7; # in paise per kWh

#calculation:
P = I*I*R
E = P*t/1000 # in kWh
C = E*p

#results
print "Power(P):", P,"Watt(W)"
print "Cost per week:", C,"Paise(p)"

Power(P): 2000 Watt(W)
Cost per week: 84.0 Paise(p)

Example 19, page no. 19

In [19]:
from __future__ import division
#initializing the variables:
P1 = 3; # in kW
P2 = 150; # in Watt
n1 = 2; # no. of P1 Equips
n2 = 6; # no. of P2 Equips
t1 = 20; # in hours each per week
t2 = 30; # in hours each per week
p = 7; # in paise per kWh

#calculation:
E1 = P1*t1*n1 # in kWh by two P1 eqips
E2 = P2*t2*n2/1000 # in kWh by six P2 eqips
Et = E1 + E2
C = Et * 7

#results
print "Cost per week:", C,"Paise(p)"

Cost per week: 1029.0 Paise(p)

Example 20, page no. 20

In [1]:
from __future__ import division
#initializing the variables:
I1 = 5; # in Amp
I2 = 10; # in Amp
I3 = 13; # in Amp
P1 = 1000; # in Watts
P2 = 3000; # in Watts
V = 240; #in Volts

#calculation:
It = P1/V
If = P2/V

#results
print "For the toaster,", I1,"A fuse is most appropriate"
print "For the Fire,", I3,"A fuse is most appropriate"

For the toaster, 5 A fuse is most appropriate
For the Fire, 13 A fuse is most appropriate