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 figure.
Find (a) the reading of the ammeter, (b) the potential difference across the terminals of the cell, and (c) the potential difference across the 4.5 Ω resistor.

Question

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 figure.

Find (a) the reading of the ammeter, (b) the potential difference across the terminals of the cell, and (c) the potential difference across the 4.5 Ω resistor.

KnowledgeBoat · Accepted Answer

Given, e.m.f. = 2V I = ? In the circuit, there are two parts. In the first part, resistors of 4.5 Ω and 9 Ω are connected in parallel. If the equivalent resistance of this part is R_p then In the second part, 1.2 Ω, 0.8 Ω and R_p = 3 Ω are connected in series. If the equivalent resistance of this part is R_s then Hence, the effective resistance of the circuit = 5 Ω Using Ohm's law, V = IR Hence, the reading of the ammeter = 0.4 A (b) The potential difference across the ends of the cells = ? ε = 2 V I = 0.4 A r = 1.2 Ω From relation, Voltage (V) = ε – Ir Substituting the values in the formula we get, Hence, potential difference across the terminals of the cell = 1.52 V (c) The potential difference across the 4.5 Ω resistor = ? Current flowing is I = 0.4 A. Now the current I divides in two parts. Let the current in 4.5 Ω resistor be I₁ and in 9 Ω resistor be I₂. So I = I₁ + I₂ and I₁ x 4.5 = I₂ x 9 On solving, p.d. across the 4.5 Ω resistor Alternate Method: V_4.5Ω = V_cell - V_ammeter Hence, p.d. across the 4.5 Ω resistor = 1.2 V

Physics

Current Electricity

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Physics

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Related Questions

Three resistors of 6.0 Ω, 2.0 Ω and 4.0 Ω are joined to an ammeter A and a cell of e.m.f. 6.0 V as shown in figure. Calculate —(a) the effective resistance of the circuit, and(b) the reading of ammeter.

The diagram below in figure shows the arrangement of five different resistances connected to a battery of e.m.f. 1.8 V. Calculate —(a) the total resistance of the circuit, and(b) the reading of ammeter A.

You have installed a new battery of emf 12 V and internal resistance 5.0 x 10-2 Ω in your car. You self-start your car and it draws a current of 90 A. What would be the teminal voltage of battery when the self-starter is working ?

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Three resistors of 6.0 Ω, 2.0 Ω and 4.0 Ω are joined to an ammeter A and a cell of e.m.f. 6.0 V as shown in figure. Calculate —
(a) the effective resistance of the circuit, and
(b) the reading of ammeter.

The diagram below in figure shows the arrangement of five different resistances connected to a battery of e.m.f. 1.8 V. Calculate —
(a) the total resistance of the circuit, and
(b) the reading of ammeter A.

You have installed a new battery of emf 12 V and internal resistance 5.0 x 10^-2 Ω in your car. You self-start your car and it draws a current of 90 A. What would be the teminal voltage of battery when the self-starter is working ?

The electrical energy supplied by a source is given by:
W = QV
W = VIt
W = I²Rt
All of the above