A company sells a gadget which it claims will lower the voltage of your electric water storage heater by 20% and thus it will reduce your electricity consumption by 20%. The heater is rated 2 kW at 230 V. a) Do you agree with the claim of the company? b) What evidence can you produce to support your opinion?

A company sells a gadget which it claims will lower the voltage of your electric water storage heater by 20% and thus it will reduce your electricity consumption by 20%. The heater is rated 2 kW at 230 V. a) Do you agree with the claim of the company? b) What evidence can you produce to support your opinion?

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter7: Electric Potential

Section: Chapter Questions

Problem 32P: (a) What is the average power output of a heart defibrillator that dissipates 400 J of energy in...

See similar textbooks

Similar questions

(a) A defibrillator sends a 6.00-A current through the chest of a patient by applying a 10,000-V potential as in the figure below. What is the resistance of the path? (b) The defibrillator paddles make contact with the patient through a conducting gel that greatly reduces the path resistance. Discuss the difficulties that would ensue if a larger voltage were used to produce the same current through the patient, but with the path having perhaps 50 times the resistance. (Hint: The current must be about the same, so a higher voltage would imply greater power. Use this equation for power: P=I2 RP = .)
To enable continuous power even during night, you would need to have a regular 100 Ah, 12 V lead acid battery (you do not use much electricity in your small cottage). Image: Wikimedia Commons, CC BY 2.0 However, you happen to have an old empty well in your backyard and you start to think if you could somehow utilize that. After all, batteries do not last forever and you would like to find a more sustainable solution. Image: Pxhere.com, CC0 Lets imagine that you could rig a gravitational energy storage by hanging a suitable weight on a cable and linking this cable to a motor-generator: if surplus electricity is available, the motor would lift the weight upwards in the well. Then, when electricity is needed, the weight would drop downwards and rotate the generator to produce electricity. Assumptions: The available well depth is 10 m, i.e. the maximum height difference you can use for the gravitational energy storage is 10 m. You can neglect all energy losses, friction, weight…
The heater element of an electric kettle has a constant resistance of 100 Ωand the applied voltage is 250 V. a.) Calculate the time taken by the kettle to boil one liter of water initially at 20ºC if all the electrical energy supplied is used in heating the water and the kettle . The water equivalent of the kettle is 100 g, b.) What percentage of the supplied electric energy is lost in heating the kettle? What percentage of the supplied energy is used in heating the water?c.) Assuming that only 85% of the electrical energy supplied is used in heating the water, determine the time it takes the kettle to boil 1 liter of water from 20oC.
A compact fluorescent lamp (CFL) uses less energy than its equivalent incandescent lamp. How much will a person save if s/he uses a 20 W CFL instead of a 100 W incandescent lamp for 6 hours in 30 days? Electricity is priced at P8.17/kWatt-Hr
A 2 0 resistor, a 10 N resistor, and a 15 N resistor are connected in parallel across a 12 V battery. Determine the equivalent resistance for the circuit. Answer in units of N. 026 (part 2 of 2) . b) Determine the current in the circuit. Answer in units of A.
Question A5 State which of the following statements are true and which are false. Give reasons for your answers. a) A simple circuit consists of a battery connected across a resistor and a capacitor of equal values in series. In this circuit, the battery voltage is divided equally between the resistor and the capacitor. b) An ideal voltmeter has infinite resistance. After two half-lives, all of a radioactive specimen will have decayed. d) An electron can be in two places at once. e) When you travel at nearly the speed of light, your time slows down.
An initially uncharged capacitor of capacitance C=199μF, and a resistor with a resistance R= 6.5k2 are connected to a battery with a voltage V=20V as shown in the figure below. The switch is closed at r=0. What would be the voltage across the capacitor one time constant after the switch is closed? Express your answer in units volts using one decimal place. Yanıtınızı ekleyin. S VI R www C ...
A 2.2 kl and a 4.0 k2 resistor are connected in parallel; this combination is connected in series with a 1.3 k2 resistor. If each resistor is rated at 0.2 W (maximum without overheating), what is the maximum voltage that can be applied across the whole network? Express your answer using two significant figures. Vmax =
A 20 m-ohm ammeter is used to measure the current through a 10 ohm resistor with which it is in series. A.) Compute the percent change in the current through this leg of the circuit, comparing the current drawn with just the resistor in the circuit with the current drawn by both elements, assuming the potential across that part stays the same. B.) Now assume the current stays the same, calculate the percent change in the potential across this part of the circuit.
a) Find the terminal voltage (in V) of a 12.0 V motorcycle battery having a 0.620 Ω internal resistance, if it is being charged by a current of 12.5 A. b) What is the output voltage (in V) of the battery charger?
An 1800 WW toaster, a 1300 W electric frying pan, and a 90 W lamp are plugged into the same electrical outlet in a 20 A, 120 V circuit. (Note: When plugged into the same outlet, the three devices are in parallel with each other across the 120 V outlet.) a. What current is drawn by the toaster? b. What current is drawn by the electric frying pan? c. What current is drawn by the lamp? d. Will this combination blow the circuit breaker?
A compact fluorescent lamp (CFL) uses less energy than its equivalent incandescent bulb. How much will a person save if he/she uses a 20 W CFL instead of a 100 W incandescent lamp for 6 hours in 30 days? Electricity is priced at P8.17 kW/h.