The current through the load resistor is
$I=\frac{\epsilon}{r+R}$ . We see from this expression that the smaller the internal resistance
r , the greater the current the voltage source supplies to its load
R . As batteries are depleted,
r increases. If
r becomes a significant fraction of the load resistance, then the current is significantly reduced, as the following example illustrates.
Analyzing a circuit with a battery and a load
A given battery has a 12.00-V emf and an internal resistance of
$0.100\phantom{\rule{0.2em}{0ex}}\text{\Omega}$ . (a) Calculate its terminal voltage when connected to a
$10.00\text{-}\text{\Omega}$ load. (b) What is the terminal voltage when connected to a
$0.500\text{-}\text{\Omega}$ load? (c) What power does the
$0.500\text{-}\text{\Omega}$ load dissipate? (d) If the internal resistance grows to
$0.500\phantom{\rule{0.2em}{0ex}}\text{\Omega}$ , find the current, terminal voltage, and power dissipated by a
$0.500\text{-}\text{\Omega}$ load.
Strategy
The analysis above gave an expression for current when internal resistance is taken into account. Once the current is found, the terminal voltage can be calculated by using the equation
${V}_{\text{terminal}}=\epsilon -Ir$ . Once current is found, we can also find the power dissipated by the resistor.
Solution
Entering the given values for the emf, load resistance, and internal resistance into the expression above yields
The terminal voltage exhibits a more significant reduction compared with emf, implying
$0.500\phantom{\rule{0.2em}{0ex}}\text{\Omega}$ is a heavy load for this battery. A “heavy load” signifies a larger draw of current from the source but not a larger resistance.
The power dissipated by the
$0.500\text{-}\text{\Omega}$ load can be found using the formula
$P={I}^{2}R$ . Entering the known values gives
Note that this power can also be obtained using the expression
$\frac{{V}^{2}}{R}\phantom{\rule{0.2em}{0ex}}\text{or}\phantom{\rule{0.2em}{0ex}}IV$ , where
V is the terminal voltage (10.0 V in this case).
Here, the internal resistance has increased, perhaps due to the depletion of the battery, to the point where it is as great as the load resistance. As before, we first find the current by entering the known values into the expression, yielding
We see that the increased internal resistance has significantly decreased the terminal voltage, current, and power delivered to a load.
Questions & Answers
define electric image.obtain expression for electric intensity at any point on earthed conducting infinite plane due to a point charge Q placed at a distance D from it.
3 capacitors 2nf,3nf,4nf are connected in parallel... what is the equivalent capacitance...and what is the potential difference across each capacitor if the EMF is 500v
heat is internal kinetic energy of a body but it doesnt mean heat is energy contained in a body because heat means transfer of energy due to difference in temperature...and in thermo-dynamics we study cause, effect, application, laws, hypothesis and so on about above mentioned phenomenon in detail.
ing
It is abranch of physical chemistry which deals with the interconversion of all form of energy
Total number of field lines crossing the surface area
Kamru
Basically flux in general is amount of anything...In Electricity and Magnetism it is the total no..of electric field lines or Magnetic field lines passing normally through the suface
prince
what is temperature change
Celine
a bottle of soft drink was removed from refrigerator and after some time, it was observed that its temperature has increased by 15 degree Celsius, what is the temperature change in degree Fahrenheit and degree Celsius
Celine
process whereby the degree of hotness of a body (or medium) changes
Salim
Q=mcΔT
Salim
where The letter "Q" is the heat transferred in an exchange in calories, "m" is the mass of the substance being heated in grams, "c" is its specific heat capacity and the static value, and "ΔT" is its change in temperature in degrees Celsius to reflect the change in temperature.
Salim
what was the temperature of the soft drink when it was removed ?
Salim
15 degree Celsius
Celine
15 degree
Celine
ok I think is just conversion
Salim
15 degree Celsius to Fahrenheit
Salim
0 degree Celsius = 32 Fahrenheit
Salim
15 degree Celsius = (15×1.8)+32 =59 Fahrenheit
Salim
I dont understand
Celine
the question said you should convert 15 degree Celsius to Fahrenheit
Salim
To convert temperatures in degrees Celsius to Fahrenheit, multiply by 1.8 (or 9/5) and add 32.
Salim
what is d final ans for Fahrenheit and Celsius
Celine
it said what is temperature change in Fahrenheit and Celsius
Celine
the 15 is already in Celsius
Salim
So the final answer for Fahrenheit is 59
Salim
what is d final ans for Fahrenheit and Celsius
Celine
what are the effects of placing a dielectric between the plates of a capacitor