Advertisements
Advertisements
प्रश्न
Two batteries of emf ε1 and ε2 (ε2 > ε1) and internal resistances r1 and r2 respectively are connected in parallel as shown in figure.
पर्याय
The equivalent emf εeq of the two cells is between ε1 and ε2, i.e. ε1 < εeq < ε2.
The equivalent emf εeq is smaller than ε1.
The εeq is given by εeq = ε1 + ε2 always.
εeq is independent of internal resistances r1 and r2.
Advertisements
उत्तर
The equivalent emf εeq of the two cells is between ε1 and ε2, i.e. ε1 < εeq < ε2.
Explanation:
The equivalent emf of this combination is given by
εeq = `(ε_1/r_1 + ε_1/r_2)/((1/r_1 + 1/r_2)) = (ε_1(1/r_1 + (ε_2/ε_1)/r_2))/((1/r_1 + 1/r_2)) = (ε_2((ε_1/ε_2)/r_1 + 1/r_2))/((1/r_1 + 1/r_2))`
As `ε_2/ε_1 > 1`
⇒ `((1/r_1 + (ε_2/r_1)/r_2))/((1/r_1 + 1/r_2)) > 1 or ε_(eq) > ε_1` also `ε_1/ε_2 < 1`
⇒ `(((ε_1/ε_2)/r_1 + 1/r_2))/((1/r_1 + 1/r_2)) < 1 or ε_(eq) < ε_1`
Hence ε1 < εeq < ε2.
APPEARS IN
संबंधित प्रश्न
Two cells of emfs 1.5 V and 2.0 V, having internal resistances 0.2 Ω and 0.3 Ω, respectively, are connected in parallel. Calculate the emf and internal resistance of the equivalent cell.
A cell of emf 'E' and internal resistance 'r' is connected across a variable resistor 'R'. Plot a graph showing variation of terminal voltage 'V' of the cell versus the current 'I'. Using the plot, show how the emf of the cell and its internal resistance can be determined.
A battery of emf 10 V and internal resistance 3 Ω is connected to a resistor. If the current in the circuit is 0.5 A, what is the resistance of the resistor? What is the terminal voltage of the battery when the circuit is closed?
The earth’s surface has a negative surface charge density of 10−9 C m−2. The potential difference of 400 kV between the top of the atmosphere and the surface results (due to the low conductivity of the lower atmosphere) in a current of only 1800 A over the entire globe. If there were no mechanism of sustaining atmospheric electric field, how much time (roughly) would be required to neutralise the earth’s surface? (This never happens in practice because there is a mechanism to replenish electric charges, namely the continual thunderstorms and lightning in different parts of the globe). (Radius of earth = 6.37 × 106 m.)
Six lead-acid types of secondary cells each of emf 2.0 V and internal resistance 0.015 Ω are joined in series to provide a supply to a resistance of 8.5 Ω. What are the current drawn from the supply and its terminal voltage?
A 10 V cell of negligible internal resistance is connected in parallel across a battery of emf 200 V and internal resistance 38 Ω as shown in the figure. Find the value of current in the circuit.
The equivalent resistance between points. a and f of the network shown in Figure 2 is :
a) 24 Ω
b) 110 Ω
c) 140 Ω
d) 200 Ω
A cell of emf ‘E’ and internal resistance ‘r’ draws a current ‘I’. Write the relation between terminal voltage ‘V’ in terms of E, I and r ?
A cell of emf E and internal resistance r is connected to two external resistance R1 and R2 and a perfect ammeter. The current in the circuit is measured in four different situations:
(i) without any external resistance in the circuit
(ii) with resistance R1 only
(iii) with R1 and R2 in series combination
(iv) with R1 and R2 in parallel combination
The currents measured in the four cases are 0.42 A, 1.05 A, 1.4 A and 4.2 A, but not necessarily in the order. Identify the currents corresponding to the four cases mentioned above.
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.
Find the equivalent resistance of the network shown in the figure between the points a and b.
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 coil of resistance 100 Ω is connected across a battery of emf 6.0 V. Assume that the heat developed in the coil is used to raise its temperature. If the heat capacity of the coil is 4.0 J K−1, how long will it take to raise the temperature of the coil by 15°C?
The temperatures of the junctions of a bismuth-silver thermocouple are maintained at 0°C and 0.001°C. Find the thermo-emf (Seebeck emf) developed. For bismuth-silver, a = − 46 × 10−6 V°C−1 and b = −0.48 × 10−6 V°C−2.
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.
Two cells of emfs approximately 5 V and 10 V are to be accurately compared using a potentiometer of length 400 cm.
A cell having an emf E and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by ______.
The terminal voltage of the battery, whose emf is 10 V and internal resistance 12, when connected through an external resistance of 40 as shown in the figure is ______.
