Advertisements
Advertisements
प्रश्न
A cell of e.m.f. 2 V and internal resistance 1.2 Ω is connected to an ammeter of resistance 0.8 Ω and two resistors of 4.5 Ω and 9 Ω as shown in following figure.
Find:
- The reading of the ammeter,
- The potential difference across the terminals of the cells, and
- The potential difference across the 4.5 Ω resistor.
Advertisements
उत्तर
The total resistance of the circuit is
`"R"_"eq" = "R"_"cell" + "R"_"ammeter" + "R"_1 || "R"_2`
`therefore "R"_"eq" = 1.2 + 0.8 + ("R"_1"R"_2)/("R"_1 + "R"_2)`
`therefore "R"_"eq" = 2 + (4.5 xx 9)/(4.5 + 9)`
= `2 + 40.5/13.5`
`therefore "R"_"eq" = 5 Omega`
(a) Therefore, the current through the ammeter is
I = `"E"_"cell"/"R"_"eq" = 2/5 = 0.4 "A"`
(b) The potential difference across the ends of the cells is
`"V"_"cell" = "E"_"cell" - "IR"_"cell"`
`therefore "V"_"cell" = 2 - 0.4 xx 1.2`
`therefore "V"_"cell" = 2 - 0.48 = 1.52 "V"`
(c) The potential difference across the 4.5 Ω resistor is
`"V"_4.5 = "V"_"cell" - "V"_"ammeter"`
`therefore "V"_4.5 = 1.52 - 0.4 xx 0.8`
`therefore "V"_4.5 = 1.52 - 0.32`
`therefore "V"_4.5 = 1.2 "V"`
APPEARS IN
संबंधित प्रश्न
The diagram below in Fig. 8.40 shows a cell of e.m.f. ε = 2 volt and internal resistance r = 1 ohm to an external resistance R = 4 ohm. The ammeter A measures the current in the circuit and the
voltmeter V measures the terminal voltage across the cell. What will be the readings of the ammeter and voltmeter when (i) the key K is open, (ii) the key K is closed.
A cell of e.m.f. ε and internal resistance 𝔯 sends current 1.0 A when it is connected to an external resistance 1.9 Ω. But it sends current 0.5 A when it is connected to an external resistance 3.9 Ω. Calculate the values of ε and 𝔯.
A battery of 4 cell, each of e.m.f. 1.5 volt and internal resistance 0.5 Ω is connected to three resistances as shown in the figure. Calculate:
(i) The total resistance of the circuit.
(ii) The current through the cell.
(iii) The current through each resistance.
(iv) The p.d. across each resistance.
Four cells each of e.m.f. 2V and internal resistance 0.1 Ω are connected in series to an ammeter of negligible resistance, a 1.6 Ω resistor and an unknown resistor R1. The current in the circuit is 2A. Draw a labelled diagram and calculate:
(i) Total resistance of the circuit,
(ii) Total e.m.f.
(iii) The value of R1 and
(iv) The p.d. across R1.
A cell supplies a current of 0.6 A through a 2Ω coil and a current of 0.3 A through on 8Ω coil. Calculate the e.m.f and internal resistance of the cell.
When a resistance of 3Ω is connected across a cell, the current flowing is 0.5 A. On changing the resistance to 7Ω, the current becomes 0.25A. Calculate the e.m.f. and the internal resistance of the cell.
(a) Calculate the total resistance across AB.
(b) If a cell of e.m.f 2.4 V with negligible internal resistance is connected across AB then calculate the current drawn from the cell.
Explain the meaning of the term internal resistance of a cell.
The diagram in Figure shows a cell of e.m.f. ε = 4 volt and internal resistance r = 2 ohm connected to an external resistance R = 8 ohm. The ammeter A measures the current in the circuit and the voltmeter V measures the terminal voltage across the cell. What will be the readings of the ammeter and voltmeter when
- the key K is open, and
- the key K is closed
A battery of e.m.f. 6.0 V supplies current through a circuit in which the resistance can be changed. A high resistance voltmeter is connected across the battery. When the current is 3 A, the voltmeter reads 5.4 V. Find the internal resistance of the battery.
