Advertisements
Advertisements
प्रश्न
The plot of the variation of potential difference across a combination of three identical cells in series, versus current is shown below. What is the emf and internal resistance of each cell ?
Advertisements
उत्तर १
Let E and r be the EMF and internal resistance of all cells respectively and e and r' be the EMF and internal resistance of each cell respectively.
As we know,
According to the definition of the terminal potential difference,
V = E − Ir
E is the EMF and r is the total internal resistance of the circuit.
I = 0 ⇒ V = E
From the graph we can see
E = 6 V
As there are three cells we can write,
E = 3 × e ⇒ e = 2 V
And, when, V = 0
⇒ E = Ir
`r=E/T=6/1=6Omega`
As per the question the cells are connected in the series, so we can write.
`r'=r/3=2Omega`
उत्तर २
Since there are three cells connected in series, Total EMF = E1 + E2 + E3
We can observe from the graph that,
E1 + E2 + E3 = 6
3E = 6 (E = E1 = E2 = E3, as they are identical cells)
hence, The EMF of each cell is 2Volt.
Now, similarly, the internal resistance is also 2 Ohm for each, because in series combination of cells not only the Emf the internal resistance also gets added up.
APPEARS IN
संबंधित प्रश्न
In a potentiometer arrangement, a cell of emf 1.25 V gives a balance point at 35.0 cm length of the wire. If the cell is replaced by another cell and the balance point shifts to 63.0 cm, what is the emf of the second cell?
A cell of emf ‘E’ and internal resistance ‘r’ is connected across a variable resistor ‘R’. Plot a graph showing the variation of terminal potential ‘V’ with resistance R. Predict from the graph the condition under which ‘V’ becomes equal to ‘E’.
Two non-ideal batteries are connected in series. Consider the following statements:-
(A) The equivalent emf is larger than either of the two emfs.
(B) The equivalent internal resistance is smaller than either of the two internal resistances.
Apply the first law of thermodynamics to a resistor carrying a current i. Identify which of the quantities ∆Q, ∆U and ∆W are zero, positive and negative.
A plate of area 10 cm2 is to be electroplated with copper (density 9000 kg m−3) to a thickness of 10 micrometres on both sides, using a cell of 12 V. Calculate the energy spent by the cell in the process of deposition. If this energy is used to heat 100 g of water, calculate the rise in the temperature of the water. ECE of copper = 3 × 10−7 kg C−1and specific heat capacity of water = 4200 J kg−1.
Find the emf of the battery shown in the figure:
Answer the following question.
A cell of emf E and internal resistance r is connected across a variable resistor R. Plot the shape of graphs showing a variation of terminal voltage V with (i) R and (ii) circuit current I.
A cell of emf E and internal resistance r is connected across an external resistance R. Plot a graph showing the variation of P.D. across R, versus R.
Study the two circuits shown in the figure below. The cells in the two circuits are identical to each other. The resistance of the load resistor R is the same in both circuits.
If the same current flows through the resistor R in both circuits, calculate the internal resistance of each cell in terms of the resistance of resistor R. Show your calculations.
