ELECTRICITY FOR TRADES (LOOSELEAF)
3rd Edition
ISBN: 9781260437454
Author: Petruzella
Publisher: MCG
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 7.2, Problem 17RQ
The cold resistance of a tungsten lamp filament is measured using an ohmmeter and found to be much lower than the hot resistance calculated using Ohm’s law and the measured voltage and current values. How can this be possible?
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
The base on an incandescent lamp with a tungsten filament is marked 120V, 60W. Measurement of the resistance of the lamp on a Wheatstone bridge indicates 20 ohms at an ambient temperature of 20 deg C. What is the normal operating temperature of incandescence of the filament if the resistance – temperature coefficient of the tungsten filament is 1/180 at 0 deg C.
What is the resistance of a platinum resistor at 480 degrees C, if its resistance at 16 degrees C is 110 ohms? Assume the fractional change is resistance per degree of temperature at To is 0.00385.
Look for Requivalent(Equivalent Resistance).Please show details
Chapter 7 Solutions
ELECTRICITY FOR TRADES (LOOSELEAF)
Ch. 7.1 - What is the base unit and symbol used for...Ch. 7.1 - Write the metric prefix and symbol used to...Ch. 7.1 - Convert each of the following: a. 2,500 to...Ch. 7.2 - State Ohms law.Ch. 7.2 - List the three formulas associated with Ohms law.Ch. 7.2 - Calculate the unknown value for each circuit (a)...Ch. 7.2 - A pilot lamp with 12 volts applied to it draws a...Ch. 7.2 - A resistor has a resistance of 220 . The current...Ch. 7.2 - An electric soldering iron with a 40- heating...Ch. 7.2 - A baseboard heater draws a current of 8 A when...
Ch. 7.2 - A sensor module has an internal resistance of...Ch. 7.2 - The current through and the voltage drop across a...Ch. 7.2 - The heating element for an electric floor heating...Ch. 7.2 - How much power is lost in the form of heat when 25...Ch. 7.2 - The voltage drop across a 330- resistor is...Ch. 7.2 - A digital multimeter display indicates a reading...Ch. 7.2 - Calculate the unknown value for each circuit (a)...Ch. 7.2 - Assume that applying 120 volts to a resistive load...Ch. 7.2 - The voltage drop across a 10-W, 330- resistor is...Ch. 7.2 - The cold resistance of a tungsten lamp filament is...Ch. 7.2 - An electric baseboard heater is rated for 1200 W...Ch. 7.2 - A lamp dimmer switch is rated for 5 A at 120 V....Ch. 7.2 - A 400-W 4- public address speaker is to be fused...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, electrical-engineering and related others by exploring similar questions and additional content below.Similar questions
- 6. The filament of a 240 V metal filament lamp is to be connected from a wire having a diameter of 0.02 mm and a resistivity at 20 °C of 4.3 micro ohms – cm and temperature coefficient at 20 °C is 0.005/•C, what length of filament is necessary if the lamp is to dissipate 60 watts at a filament tempearture of 2420 °Carrow_forward1- If we use 5000 μF, we can get a very low ripple voltage. But this is so bad and this a disadvantage, why? 2- What happens if we use a very small resistance (few Ohms) or big resistance (100 kOhms) ?arrow_forwardThe resistance of wire increases from 40 – ohm at 20 0C to 50 – ohm at 70 0C. Find the temperature coefficient of resistance at 0 0C.arrow_forward
- You are given two metal samples. The first one is pure and the other one is unrefined. Will there be a difference in their electrical conductivity? If so, how is this possible?arrow_forwardWhich material is always conductive? Metal semiconductor Insulatorarrow_forward7. The conductance of a certain wire is 0.5S. Another wire of the same material and at the same temperature has a diameter twice as great and a length three times as great. What is the conductance of the second wire?arrow_forward
- You want to produce three cylindrical wires with a diameter of 1.00 mm, each with a resistance of 1.00 V at room temperature. One wire is gold, one is copper and one is aluminum. Refer to the resistivity table (a) How long should each wire be?arrow_forwardThe resistance of a copper wire is 125 ohms at 100°C. Determine the resistance at 70°Carrow_forwardA. Using long coupon bond(s), make a written discussion of what you learned in this lesson. Your discussion includes but not limited to the following: 1. Electric current, direct and alternating current, average current 2. Emf, dependent and independent sources 3. Conductance and conductivity 4. Resistance and resistivity 5. Percent conductivity 6. D-c measurements of voltage, current, resistance B. Calculate the resistivity and percent conductivity of the elements and alloys listec in the table below. 1. Resistivity Elements Ohm-cm Ohm-meter Alloys Ohm-cm Ohm-meter Brass Silver German silver Copper, Manganin Copper, Lucero Gold, pure Advance Aluminum Constantan Magnesium Excello Tungsten Nichrome Zinc Nichrome II Nickel Chromel Iron, cast Platinum Iron, Leadarrow_forward
- 2. An incandescent light bulb uses a cold filament of tungsten that is 580 mm. long with a diameter of 46 um and has a resistivity of 5.25 x 10-8 Q-m at 20°C. If the initial resistance of tungsten is 100 at 20°C and a temperature coefficient of resistance of 0.0045 °C. What is the temperature of the filament?arrow_forwardThe resistance of a copper wire is (0.92 0) at a temperature of (4 oC). At what temperature will be resistance be (1.06 Q)?arrow_forwardA 50 μA basic D'Arsonval movement with an internal resistance of 500 is to be used as a voltmeter. The value of the multiplier resistance required to measure a full-scale voltage range of 0-5 volts is?arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Electricity for Refrigeration, Heating, and Air C...Mechanical EngineeringISBN:9781337399128Author:Russell E. SmithPublisher:Cengage Learning
Electricity for Refrigeration, Heating, and Air C...
Mechanical Engineering
ISBN:9781337399128
Author:Russell E. Smith
Publisher:Cengage Learning
What is an electric furnace and how does it work?; Author: Fire & Ice Heating and Air Conditioning Inc;https://www.youtube.com/watch?v=wjAWecPGi0M;License: Standard Youtube License