{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Chapter 3 : Ohm's Law"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_1 Page No. 88"
]
},
{
"cell_type": "code",
"execution_count": 1,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Current I = 15.00 Amps\n"
]
}
],
"source": [
"# A heater with the resistance of 8 Ohms\u0003 is connected across the 120-V power line. How much is current I?\n",
"\n",
"# Given data\n",
"\n",
"V = 120# # Voltage of Power line=120 Volts\n",
"R = 8# # Heater Resistance=8 Ohms\n",
"\n",
"I = V/R#\n",
"print 'The Current I = %0.2f Amps'%I"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_2 Page No. 88"
]
},
{
"cell_type": "code",
"execution_count": 3,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Current I = 0.05 Amps\n"
]
}
],
"source": [
"# A small lightbulb with a resistance of 2400 Ohms\u0003 is connected across the 120-V power line. How much is current I?\n",
"\n",
"# Given data\n",
"\n",
"V = 120.# # Voltage of Power line=120 Volts\n",
"R = 2400# # Lightbulb Resistance=2400 Ohms\n",
"\n",
"I = V/R#\n",
"print 'The Current I = %0.2f Amps'%I"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_3 Page No. 88"
]
},
{
"cell_type": "code",
"execution_count": 4,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Voltage = 30.00 Volts\n"
]
}
],
"source": [
"# If a 12-Ohms\u0003 resistor is carrying a current of 2.5 A, how much is its voltage?\n",
"\n",
"# Given data\n",
"\n",
"I = 2.5# # Current=2.5 Amps\n",
"R = 12# # Resistance=12 Ohms\n",
"\n",
"V = I*R#\n",
"print 'The Voltage = %0.2f Volts'%V"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_4 Page No. 89"
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Resistance = 75.00 ohms\n"
]
}
],
"source": [
"# How much is the resistance of a lightbulb if it draws 0.16 A from a 12-V battery?\n",
"\n",
"# Given data\n",
"\n",
"V = 12# # Voltage of Battery=12 Volts\n",
"I = 0.16# # Current drawn form Battery=0.16 Amps\n",
"\n",
"R = V/I\n",
"print 'The Resistance = %0.2f ohms'%R"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_5 Page No. 89"
]
},
{
"cell_type": "code",
"execution_count": 6,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Voltage = 40.00 Volts\n"
]
}
],
"source": [
"# The I of 8 mA flows through a 5-kOhms Resistor. How much is the IR voltage?\n",
"\n",
"# Given data\n",
"\n",
"I = 8*10**-3# # Current flowing through Resistor=8m Amps\n",
"R = 5*10**3# # Resistance=5k Ohms\n",
"\n",
"V = I*R#\n",
"print 'The Voltage = %0.2f Volts'%V"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_6 Page No. 90"
]
},
{
"cell_type": "code",
"execution_count": 8,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Current I = 0.005 Amps\n",
"i.e 5 mAmps\n"
]
}
],
"source": [
"# How much current is produced by 60 V across 12 kOhms?\n",
"\n",
"# Given data\n",
"\n",
"V = 60.0# # Voltage=60 Volts\n",
"R = 12*10**3# # Resistance=12k Ohms\n",
"\n",
"I = V/R#\n",
"print 'The Current I = %0.3f Amps'%I\n",
"print 'i.e 5 mAmps'"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_7 Page No. 91"
]
},
{
"cell_type": "code",
"execution_count": 9,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Power used = 1200.00 Watts\n",
"OR 1.2 kW\n"
]
}
],
"source": [
"# A toaster takes 10 A from the 120-V power line. How much power is used?\n",
"\n",
"# Given data\n",
"\n",
"V = 120# # Voltage of Power line=120 Volts\n",
"I = 10# # Current drawn from Powerline=10 Amps\n",
"\n",
"P = V*I#\n",
"print 'The Power used = %0.2f Watts'%P\n",
"print 'OR 1.2 kW'"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_8 Page No. 91"
]
},
{
"cell_type": "code",
"execution_count": 11,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Current I = 2.50 Amps\n"
]
}
],
"source": [
"# How much current flows in the filament of a 300-W bulb connected to the 120-V power line?\n",
"\n",
"# Given Data\n",
"\n",
"V = 120.0# # Voltage of Power line=120 Volts\n",
"P = 300# # Power of Bulb=300 Watts\n",
"\n",
"I = P/V#\n",
"print 'The Current I = %0.2f Amps'%I"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_9 Page No. 91"
]
},
{
"cell_type": "code",
"execution_count": 13,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Current I = 0.50 Amps\n",
"OR 500 mA\n"
]
}
],
"source": [
"# How much current flows in the filament of a 60-W bulb connected to the 120-V power line?\n",
"\n",
"# Given Data\n",
"\n",
"V = 120# # Voltage of Power line=120 Volts\n",
"P = 60.0# # Power of Bulb=60 Watts\n",
"\n",
"I = P/V#\n",
"print 'The Current I = %0.2f Amps'%I\n",
"print 'OR 500 mA'"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_10 Page No. 93"
]
},
{
"cell_type": "code",
"execution_count": 14,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Cost = 4.32 $\n"
]
}
],
"source": [
"# Asuming that the cost of electricity is 6 cent per kWh, how much will it cost to light a 100-W lightbulb for 30 days?\n",
"\n",
"h = 24*30# # Total hours = 24 hrs * 30 days\n",
"\n",
"kWh = 0.1*h# # 100W=0.1kW\n",
"\n",
"Cost = kWh*0.06# # 6 cent = $0.06\n",
"\n",
"print 'Cost = %0.2f $'%Cost"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_11 Page No. 95"
]
},
{
"cell_type": "code",
"execution_count": 15,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Power = 200.00 Watts\n"
]
}
],
"source": [
"# Calculate the power in a circuit where the source of 100 V produces 2 A in a 50 Ohms Resistor.\n",
"\n",
"# Given data\n",
"\n",
"I = 2# # Current=2 Amps\n",
"R = 50# # Resistance=50 Ohms\n",
"V = 100# # Voltage Source=100 Volts\n",
"\n",
"P = I*I*R#\n",
"print 'The Power = %0.2f Watts'%P"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_12 Page No. 95"
]
},
{
"cell_type": "code",
"execution_count": 17,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Power = 400.00 Watts\n"
]
}
],
"source": [
" \n",
"# Calculate the power in a circuit where the source of 100 V produces 4 A in a 25 Ohms Resistor.\n",
"\n",
"# Given data\n",
"\n",
"I = 4# # Current=4 Amps\n",
"R = 25# # Resistance=25 Ohms\n",
"V = 100# # Voltage Source=100 Volts\n",
"\n",
"P = I*I*R#\n",
"print 'The Power = %0.2f Watts'%P"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_13 Page No. 96"
]
},
{
"cell_type": "code",
"execution_count": 18,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Current I = 5.00 Amps\n"
]
}
],
"source": [
"# How much current is needed for a 600-W, 120-V toaster?\n",
"\n",
"# Given data\n",
"\n",
"V = 120.0# # Applied Voltage=120 Volts\n",
"P = 600# # Power of toaster=600 Watts\n",
"\n",
"I = P/V#\n",
"print 'The Current I = %0.2f Amps'%I"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_14 Page No. 97"
]
},
{
"cell_type": "code",
"execution_count": 20,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Resistance = 24.00 Ohms\n"
]
}
],
"source": [
"# How much is the resistance of a 600-W, 120-V toaster?\n",
"\n",
"# Given data\n",
"\n",
"V = 120.0# # Applied Voltage=120 Volts\n",
"P = 600# # Power of toaster=600 Watts\n",
"\n",
"R = (V*V)/P#\n",
"print 'The Resistance = %0.2f Ohms'%R"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_15 Page No. 97"
]
},
{
"cell_type": "code",
"execution_count": 21,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Current I = 5.00 Amps\n"
]
}
],
"source": [
"from math import sqrt\n",
"# How much current is needed for a 24 Ohms\u0003 Resistor that dissipates 600 W?\n",
"\n",
"# Given data\n",
"\n",
"R = 24.0# # Resistance=24 Ohms\n",
"P = 600.0# # Power=600 Watts\n",
"\n",
"I = sqrt(P/R)#\n",
"print 'The Current I = %0.2f Amps'%I"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_16 Page No. 98"
]
},
{
"cell_type": "code",
"execution_count": 23,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Resistor value = 1500.00 Ohms\n",
"i.e 1.5 kohms\n",
"The Power = 0.60 Watts\n",
"OR 600 mW\n"
]
}
],
"source": [
"# Determine the required resistance and appropriate wattage rating of a resistor to meet the following requirements: The resistor must have a 30-V IR drop when its current is 20 mA. The resistors available have the following wattage ratings: 1⁄8, 1⁄4, 1⁄2, 1, and 2 W.\n",
"\n",
"# Given data\n",
"\n",
"I = 20.0*10**-3# # Current=20m Amps\n",
"V = 30.0# # Voltage Drop=30 Volts\n",
"\n",
"R = V/I#\n",
"print 'The Resistor value = %0.2f Ohms'%R\n",
"print 'i.e 1.5 kohms'\n",
"\n",
"P = I*I*R#\n",
"print 'The Power = %0.2f Watts'%P\n",
"print 'OR 600 mW'\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example No. 3_17 Page No. 99"
]
},
{
"cell_type": "code",
"execution_count": 28,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The Resistor value = 1500000 Ohms\n",
"i.e 1.5 Mohms\n",
"The Power = 0.03375 Watts\n",
"i.e 33.75 mW\n"
]
}
],
"source": [
"#Determine the required resistance and appropriate wattage rating of a carbonfilm resistor to meet the following requirements: The resistor must have a 225-V IR drop when its current is 150 uA. The resistors available have the following wattage ratings: 1⁄8, 1⁄4, 1⁄2, 1, and 2 W.\n",
"\n",
"# Given data\n",
"\n",
"I = 150.0*10**-6# # Current=150 uAmps\n",
"V = 225# # Voltage Drop=225 Volts\n",
"\n",
"R = V/I#\n",
"print 'The Resistor value = %0.f Ohms'%R\n",
"print 'i.e 1.5 Mohms'\n",
"\n",
"P = I*I*R#\n",
"print 'The Power = %0.5f Watts'%P\n",
"print 'i.e 33.75 mW'"
]
}
],
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