DC Circuits and Measurements — Flashcards

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An electric cell is a source of electrical energy which maintains a continuous flow of charge in a circuit. It consists of two electrodes immersed in an electrolyte. Chemical reaction in the electroly…

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Electromotive force is the work done by a cell in forcing unit positive charge to flow in the whole circuit, including the cell. Its unit is volt, not newton. It is called force only historically.

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Formula: E = dW/dq Meaning: E = emf, dW = work done by the cell, dq = charge flown. Unit: 1 V = 1 J C^-1. Quick meaning: 1 volt means 1 joule of work is done in moving 1 coulomb of charge.

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Given: W = 1350 J, q = 900 C Formula: E = W/q Step 1: E = 1350 J / 900 C Step 2: E = 1.5 J C^-1 Step 3: E = 1.5 V Answer: 1.5 V…

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1. EMF does not depend on the dimensions of the electrodes, their separation, or the quantity of electrolyte. 2. If a dry cell of emf about 1.5 V is cut into two parts, each part has the same emf as t…

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Terminal potential difference is the work done for the flow of unit charge in the external circuit only. Formula: V = dW'/dq Meaning: V = potential difference, dW' = energy consumed in that part, dq =…

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Given: E = 10 V, r = 3 ohm, I = 0.5 A Formula: E = I(R + r) Step 1: R + r = E/I = 10/0.5 = 20 ohm Step 2: R = 20 - 3 = 17 ohm Formula for terminal voltage: V = IR Step 3: V = 0.5 A x 17 ohm = 8.5 V An…

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Relation: E = V + Ir Also: V = E - Ir Meaning: E = emf, V = terminal potential difference, I = current, r = internal resistance. When current is drawn from a cell, V < E.