C11PracticalCircuits

A cell with internal resistance is connected to a light-dependent resistor (LDR), a fixed resistor

and a voltmeter, as shown.

The voltmeter reading increases.

Which quantity decreases as the voltmeter reading increases?

• the charge moving through the cell per unit time

• the energy transferred to the fixed resistor per unit charge

• the intensity of the light incident on the LDR

• the terminal potential difference across the cell

The circuit shown contains a cell with negligible internal resistance.

The energy transferred per unit charge in driving charge around the complete circuit is E. The

potential difference (p.d.) across X is V.

The cell is then replaced with a different cell of the same electromotive force (e.m.f.) that has

significant internal resistance.

What is the effect on E and V of replacing the cell?

• E decreases; V decreases

• E decreases; V increases

• E no change; V decreases

• E no change; V increases

A potentiometer circuit is used to determine the electromotive force (e.m.f.) E of a cell. The circuit

includes a second cell of e.m.f. 1.5 V and internal resistance 0.50  that is connected to a uniform

resistance wire XY, as shown.

The resistance wire XY has a length of 0.96 m and a resistance of 0.50 .

The movable connection Z is moved along wire XY. The galvanometer reading is zero when

length XZ is 0.64 m.

What is the value of e.m.f. E ?

• 0.50 V

• 0.75 V

• 1.0 V

• 1.1 V

A cell with electromotive force (e.m.f.) 1.50 V delivers a current of 0.26 A to a resistor of

resistance 5.0 ohm connected between its terminals.

What is the internal resistance of the cell?

• 0.04 Ω

• 0.20 Ω

• 0.39 Ω

• 0.77 Ω

A circuit contains a battery of electromotive force E and internal resistance r connected to two resistors each of resistance 2.5 ohm.

The resistors are connected in parallel as shown.

The current in one of the resistors is 0.80 A.

Which expression, where E is in volts and r is in ohms, gives the internal resistance r ?

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The diagram shows part of a circuit that uses a potentiometer wire to measure a potential difference (p.d.) in an external circuit.

The potentiometer wire XZ has length L1. It is connected to a cell of known electromotive force (e.m.f.) E that has negligible internal resistance.

Terminals P and Q are connected to the external p.d. to be measured. The length of the potentiometer wire between points X and Y is L2.

The ratio of the lengths L1 and L2 is used to determine the p.d. between P and Q in terms of E.

Which condition must be met in order to determine this p.d.?

• The current I1 must be zero.

• The current I2 must be zero.

• The p.d. across YZ must be zero.

• The resistance of the external circuit must be zero.

Which circuit results in output voltage Vout increasing with increasing temperature?

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The diagram shows a potentiometer circuit used to compare the electromotive forces (e.m.f.), E1 and E2, of two cells.

XY is a uniform resistance wire. The fixed resistor has resistance R.

A sliding contact is moved along the wire XY. When the sliding contact is at position P, the galvanometer reads zero.

The circuit is changed so that the galvanometer reads zero when the sliding contact is at a new position to the left of P.

Which change could have been made to the circuit?

• The wire XY was replaced with one of lower resistance.

• E2 was increased.

• E1 was decreased.

• R was decreased.

• A

• B

• C

• D

• E-Ir=IR

• E=Ir-IR

• E+Ir=IR

• E=IR