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Carbon-zinc dry cells (sometimes referred to as non-alkaline cells) have an emf of 1.54 V, and they are produced as single cells or in various combinations to form other voltages. (a) How many 1.54-V cells are needed to make the common 9-V battery used in many small electronic devices? (b) What is the actual emf of the approximately 9-V battery? (c) Discuss how internal resistance in the series connection of cells will affect the terminal voltage of this approximately 9-V battery.

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What is the output voltage of a 3.0000-V lithium cell in a digital wristwatch that draws 0.300 mA, if the cell’s internal resistance is 2 . 00 Ω size 12{2 "." "00" %OMEGA } {} ?

2.9994 V

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(a) What is the terminal voltage of a large 1.54-V carbon-zinc dry cell used in a physics lab to supply 2.00 A to a circuit, if the cell’s internal resistance is 0 . 100 Ω size 12{0 "." "100" %OMEGA } {} ? (b) How much electrical power does the cell produce? (c) What power goes to its load?

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What is the internal resistance of an automobile battery that has an emf of 12.0 V and a terminal voltage of 15.0 V while a current of 8.00 A is charging it?

0 . 375 Ω size 12{0 "." "375" %OMEGA } {}

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(a) Find the terminal voltage of a 12.0-V motorcycle battery having a 0 . 600-Ω size 12{0 "." "600"- %OMEGA } {} internal resistance, if it is being charged by a current of 10.0 A. (b) What is the output voltage of the battery charger?

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A car battery with a 12-V emf and an internal resistance of 0 . 050 Ω size 12{0 "." "050" %OMEGA } {} is being charged with a current of 60 A. Note that in this process the battery is being charged. (a) What is the potential difference across its terminals? (b) At what rate is thermal energy being dissipated in the battery? (c) At what rate is electric energy being converted to chemical energy? (d) What are the answers to (a) and (b) when the battery is used to supply 60 A to the starter motor?

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The hot resistance of a flashlight bulb is 2 . 30 Ω size 12{2 "." "30" %OMEGA } {} , and it is run by a 1.58-V alkaline cell having a 0 . 100-Ω size 12{0 "." "100"- %OMEGA } {} internal resistance. (a) What current flows? (b) Calculate the power supplied to the bulb using I 2 R bulb size 12{I rSup { size 8{2} } R rSub { size 8{"bulb"} } } {} . (c) Is this power the same as calculated using V 2 R bulb size 12{ { {V rSup { size 8{2} } } over {R rSub { size 8{"bulb"} } } } } {} ?

(a) 0.658 A

(b) 0.997 W

(c) 0.997 W; yes

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The label on a portable radio recommends the use of rechargeable nickel-cadmium cells (nicads), although they have a 1.25-V emf while alkaline cells have a 1.58-V emf. The radio has a 3 . 20-Ω size 12{3 "." "20"- %OMEGA } {} resistance. (a) Draw a circuit diagram of the radio and its batteries. Now, calculate the power delivered to the radio. (b) When using Nicad cells each having an internal resistance of 0 . 0400 Ω size 12{0 "." "0400" %OMEGA } {} . (c) When using alkaline cells each having an internal resistance of 0 . 200 Ω size 12{0 "." "200" %OMEGA } {} . (d) Does this difference seem significant, considering that the radio’s effective resistance is lowered when its volume is turned up?

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An automobile starter motor has an equivalent resistance of 0 . 0500 Ω size 12{0 "." "0500" %OMEGA } {} and is supplied by a 12.0-V battery with a 0 . 0100-Ω size 12{0 "." "0100"- %OMEGA } {} internal resistance. (a) What is the current to the motor? (b) What voltage is applied to it? (c) What power is supplied to the motor? (d) Repeat these calculations for when the battery connections are corroded and add 0 . 0900 Ω size 12{0 "." "0900" %OMEGA } {} to the circuit. (Significant problems are caused by even small amounts of unwanted resistance in low-voltage, high-current applications.)

(a) 200 A

(b) 10.0 V

(c) 2.00 kW

(d) 0 . 1000 Ω ; 80 . 0 A, 4 . 0 V, 320 W size 12{0 "." "1000" %OMEGA ;" 80" "." "0 A, 4" "." "0 V, 320 W"} {}

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A child’s electronic toy is supplied by three 1.58-V alkaline cells having internal resistances of 0 . 0200 Ω size 12{0 "." "0200" %OMEGA } {} in series with a 1.53-V carbon-zinc dry cell having a 0 . 100-Ω size 12{0 "." "100"- %OMEGA } {} internal resistance. The load resistance is 10 . 0 Ω size 12{"10" "." 0 %OMEGA } {} . (a) Draw a circuit diagram of the toy and its batteries. (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?

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(a) What is the internal resistance of a voltage source if its terminal voltage drops by 2.00 V when the current supplied increases by 5.00 A? (b) Can the emf of the voltage source be found with the information supplied?

(a) 0 . 400 Ω size 12{0 "." "400" %OMEGA } {}

(b) No, there is only one independent equation, so only r size 12{r} {} can be found.

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A person with body resistance between his hands of 10 . 0 k Ω size 12{"10" "." 0" k" %OMEGA } {} accidentally grasps the terminals of a 20.0-kV power supply. (Do NOT do this!) (a) Draw a circuit diagram to represent the situation. (b) If the internal resistance of the power supply is 2000 Ω size 12{"2000" %OMEGA } {} , what is the current through his body? (c) What is the power dissipated in his body? (d) If the power supply is to be made safe by increasing its internal resistance, what should the internal resistance be for the maximum current in this situation to be 1.00 mA or less? (e) Will this modification compromise the effectiveness of the power supply for driving low-resistance devices? Explain your reasoning.

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Electric fish generate current with biological cells called electroplaques, which are physiological emf devices. The electroplaques in the South American eel are arranged in 140 rows, each row stretching horizontally along the body and each containing 5000 electroplaques. Each electroplaque has an emf of 0.15 V and internal resistance of 0 . 25 Ω size 12{0 "." "25" %OMEGA } {} . If the water surrounding the fish has resistance of 800 Ω size 12{"800" %OMEGA } {} , how much current can the eel produce in water from near its head to near its tail?

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Integrated Concepts

A 12.0-V emf automobile battery has a terminal voltage of 16.0 V when being charged by a current of 10.0 A. (a) What is the battery’s internal resistance? (b) What power is dissipated inside the battery? (c) At what rate (in º C/min size 12{°"C/min"} {} ) will its temperature increase if its mass is 20.0 kg and it has a specific heat of 0 . 300 kcal/kg º C size 12{0 "." "300"" kcal/kg" cdot °C} {} , assuming no heat escapes?

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Unreasonable Results

A 1.58-V alkaline cell with a 0 . 200-Ω size 12{0 "." "200"- %OMEGA } {} internal resistance is supplying 8.50 A to a load. (a) What is its terminal voltage? (b) What is the value of the load resistance? (c) What is unreasonable about these results? (d) Which assumptions are unreasonable or inconsistent?

(a) –0.120 V

(b) - 1 . 41 × 10 2 Ω size 12{ +- 1 "." "41"´"10" rSup { size 8{-2} } %OMEGA } {}

(c) Negative terminal voltage; negative load resistance.

(d) The assumption that such a cell could provide 8.50 A is inconsistent with its internal resistance.

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Unreasonable Results

(a) What is the internal resistance of a 1.54-V dry cell that supplies 1.00 W of power to a 15 . 0-Ω size 12{"15" "." 0- %OMEGA } {} bulb? (b) What is unreasonable about this result? (c) Which assumptions are unreasonable or inconsistent?

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Questions & Answers

draw magnetic field pattern for two wire carrying current in the same direction
Ven Reply
An American traveler in New Zealand carries a transformer to convert New Zealand’s standard 240 V to 120 V so that she can use some small appliances on her trip.
nkombo Reply
What is the ratio of turns in the primary and secondary coils of her transformer?
nkombo
How electric lines and equipotential surface are mutually perpendicular?
Abid Reply
The potential difference between any two points on the surface is zero that implies È.Ŕ=0, Where R is the distance between two different points &E= Electric field intensity. From which we have cos þ =0, where þ is the angle between the directions of field and distance line, as E andR are zero. Thus
MAHADEV
sorry..E and R are non zero...
MAHADEV
By how much leeway (both percentage and mass) would you have in the selection of the mass of the object in the previous problem if you did not wish the new period to be greater than 2.01 s or less than 1.99 s?
Elene Reply
what Is linear momentum
Victoria Reply
why no diagrams
Blessing Reply
where
Fayyaz
Myanmar
Pyae
hi
Iroko
hello
Abdu
Describe an experiment to determine short half life
Tyson Reply
what is science
Kenedy Reply
it's a natural phenomena
Hassan
sap
Emmanuel
please can someone help me with explanations of wave
Benedine
A 20MH coil has a resistance of 50 ohms and us connected in series with a capacitor to a 520MV supply
Musa Reply
what is physics
Caya Reply
it is the science which we used in our daily life
Sujitha
Physics is the branch of science that deals with the study of matter and the interactions it undergoes with energy
Junior
it is branch of science which deals with study of happening in the human life
AMIT
A 20MH coil has a resistance of 50 ohms and is connected in series with a capacitor to a 250MV supply if the circuit is to resonate at 100KHZ, Determine 1: the capacitance of the capacitor 2: the working voltage of the circuit, given that pie =3.142
Musa
Physics is the branch of science that deals with the study of matter and the interactions it undergoes with energy
Kelly
Heat is transfered by thermal contact but if it is transfered by conduction or radiation, is it possible to reach in thermal equilibrium?
Eden Reply
Yes, It is possible by conduction if Surface is Adiabatic
Astronomy
Yeah true ilwith d help of Adiabatic
Kelly
what are the fundamentals qualities
Magret Reply
what is physic3
Kalilu
what is physic
Kalilu
Physics? Is a branch of science dealing with matter in relation to energy.
Moses
Physic... Is a purging medicine, which stimulates evacuation of the bowels.
Moses
are you asking for qualities or quantities?
Noman
give examples of three dimensional frame of reference
Ekwunazor Reply
Universe
Noman
Yes the Universe itself
Astronomy
Examine different types of shoes, including sports shoes and thongs. In terms of physics, why are the bottom surfaces designed as they are? What differences will dry and wet conditions make for these surfaces?
Lathan Reply
sports shoes are designed in such a way they are gripped well with your feet and their bases have and high friction surfaces, Thong shoes are for comfort, these are easily removed and light weight. these are usually low friction surfaces but in wet conditions they offer greater friction.
Noman
thong sleepers are usually used in restrooms.
Noman
what is wave
Ochigbo Reply
The phenomenon of transfer of energy
Noman
Practice Key Terms 4

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Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
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