Concept explainers
(a)
The resistance of heater when it is applied
Answer to Problem 81QAP
Resistance of heater is
Explanation of Solution
Given:
Potential difference across the heater =
Mass of water =
Initial temperature of water =
Final temperature of water =
Specific heat of water =
Time up to heat is on =
Formula used:
Electrical energy consumed in heat is defined as,
Heat absorbed by water due to temperature difference is defined as,
Calculation:
It is given that
Now, substituting all these values,
Conclusion:
Thus, resistance of heater is
(b)
The difference in time interval when heater is connected with
Answer to Problem 81QAP
The difference in time interval is
Explanation of Solution
Given:
Initial voltage across the heater =
Initial time taken by heater to raise temperature of water with voltage
Potential difference across the heater when it is connected by car's battery =
Formula used:
Electrical energy consumed in heat is defined as,
Calculation:
Since, Electrical energy is defined as,
Consider the time taken by car battery is
Time difference =
Conclusion:
Thus, time difference is
Want to see more full solutions like this?
Chapter 18 Solutions
College Physics Volume 2
- When operating on a 120-V circuit, an electric heater receives 1.30 103 W of power, a toaster receives 1.00 103 W, and an electric oven receives 1.54 103 W. If all three appliances are connected in parallel on a 120-V circuit and turned on, what is the total current drawn from an external source? (a) 24.0 A (b) 32.0 A (c) 40.0 A (d) 48.0 A (e) none of those answersarrow_forwardA child's electronic toy is supplied by three 1.58-V alkaline cells having internal resistances of 0.0200 inseries with a 1.53-V carbon-zinc dry cell having a 0.100- internal resistance. The load resistance is 10.0 . (a) Draw a circuit diagram of the toy and itsbatteries, (b) What current flows? (c) How much power is supplied to the load? (d) What is the internal resistance of the dry cell if it goes bad, resulting in only 0.500 W being supplied to the load?arrow_forwardPower P0 = I0 V0 is delivered to a resistor of resistance R0. If the resistance is doubled (Rnew = 2R0) while the voltage is adjusted such that the current is constant, what are the ratios (a) Pnew/P0 and (b) Vnew/V0? If, instead, the resistance is held constant while Pnew = 2P0, what are the ratios (c) Vnew/V0, and (d) Inew/I0?arrow_forward
- Lightbulb A is marked 25.0 W 120. V, and lightbulb B is marked 100. W 120. V. These labels mean that each lightbulb has its respective power delivered to it when it is connected to a constant 120.-V source. (a) Find the resistance of each lightbulb. (b) During what time interval does 1.00 C pass into lightbulb A? (c) Is this charge different upon its exit versus its entry into the lightbulb? Explain. (d) In what time interval does 1.00 J pass into lightbulb A? (e) By what mechanisms does this energy enter and exit the lightbulb? Explain. (f) Find the cost of running lightbulb A continuously for 30.0 days, assuming the electric company sells its product at 0.110 per kWh.arrow_forwardIf the terminals of a battery with zero internal resistance are connected across two identical resistors in series, the total power delivered by the battery is 8.00 W. If the same battery is connected across the same resistors in parallel, what is the total power delivered by the battery? (a) 16.0 W (b) 32.0 W (c) 2.00 W (d) 4.00 W (e) none of those answersarrow_forwardA rechargeable battery has an emf of 13.2 V and an internal resistance of 0.850 . It is charged by a 14.7-V power supply for a time interval of 1.80 h. Alter charging, the battery returns to its original state as it delivers a constant current to a load resistor over 7.30 h. Find the efficiency of the battery as an energy storage device. (The efficiency here is defined as the energy delivered to the load during discharge divided by the energy delivered by the 14.7-V power supply during the charging process.)arrow_forward
- The recovery time of a hot water heater is the time required to heat all the water in the unit to the desired temperature. Suppose that a 20-gallon (1.00 gal = 3.79 x 10-3 m3) unit starts with water at 14 °C and delivers hot water at 55 °C. The unit is electric and uses a resistance heater (120 V AC, 3.4 Ω) to heat the water. If water has a specific heat capacity of 4186 J/(kg°C) and a density of 1000 kg/m3, and assuming that no heat is lost to the environment, what is the recovery time of this hot water heater?arrow_forwardThe resistance of an electric heater is 90 Ω when connected to 120 V. How much energy does it use during 20 min of operation?arrow_forwardConsider a portable electric blanket that runs on a 4.5 V battery. If you use copper wire with a 0.5 mm diameter as the heating element, how long should the wire be (in unit of meters) if you want to generate 15 W of heating power? (Take the resistivity of the copper wire as p= 1.7 x 10^(-8) Ω.m)arrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningPhysics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning