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
What mass of steam of 100 degree celcius must be mixed with 150g of ice at 0 degree celcius, in a thermally insulated container, to produce liquid water at 50 degree celcius
To convert 0°C ice to 0°c water. Q=M*s=150g*334J/g=50100 J.......... Now 0° water to 50° water... Q=M*s*dt=150g*4.186J/g*50= 31395 J....... Which adds upto 81495 J..... This is amount of heat the steam has to carry. 81495= M *s=M*2230J/g..therefore.....M=36.54g of steam
SHREESH
This is at 1 atm
SHREESH
If there is change in pressure u can refer to the steam table ....
SHREESH
instrument for measuring highest temperature of a body is?
Its state that "energy can neither be created nor destroyed but can be transformed from one form to another. "
Ayodamola
what about the other laws
can anyone here help with it please
Sandy
The second law of thermodynamics states that the entropy of any isolated system always increases. The third law of thermodynamics states that the entropy of a system approaches a constant value as the temperature approaches absolute zero.
sahil
The first law is very simple to understand by its equation.
The law states that "total energy in thermodynamic sytem is always constant"
i.e d¶=du+dw where
d¶=total heat
du=internal energy
dw=workdone...
PLEASE REFER TO THE BOOKS FOR MORE UNDERSTANDING OF THE CONCEPT.
it means that the total charge of a body will always be the integral multiples of basic unit charge ( e )
q = ne
n : no of electrons or protons
e : basic unit charge
1e = 1.602×10^-19
Riya
is the time quantized ? how ?
Mehmet
What do you meanby the statement,"Is the time quantized"
Mayowa
Can you give an explanation.
Mayowa
there are some comment on the time -quantized..
Mehmet
time is integer of the planck time, discrete..
Mehmet
planck time is travel in planck lenght of light..
Mehmet
it's says that charges does not occur in continuous form rather they are integral multiple of the elementary charge of an electron.
Tamoghna
it is just like bohr's theory.
Which was angular momentum of electron is intral multiple of h/2π
The properties of a system during a reversible constant pressure non-flow process at P= 1.6bar, changes from constant volume of 0.3m³/kg at 20°C to a volume of 0.55m³/kg at 260°C. its constant pressure process is 3.205KJ/kg°C
Determine: 1. Heat added, Work done, Change in Internal Energy and Change in Enthalpy
this is the energy dissipated(usually in the form of heat energy) in conductors such as wires and coils due to the flow of current against the resistance of the material used in winding the coil.