The diagram in figure shows a cell of e.m.f. ε = 2 volt and internal resistance r = 1 ohm connected 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, and (ii) the key K is closed

Home » The diagram in figure shows a cell of e.m.f. ε = 2 volt and internal resistance r = 1 ohm connected 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, and (ii) the key K is closed

Class 10 | Current Energy | ICSE | Physics | Selina

The diagram in figure shows a cell of e.m.f. ε = 2 volt and internal resistance r = 1 ohm connected 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, and (ii) the key K is closed

(i) Ammeter reading = 0 , due to lack of current

Voltage V = ε – Ir

V = 2 – 0 × 1

V = 2 volt
(ii) The reading on the ammeter

I = ε / (R + r)
I = 4 + 1 / 2

I = 2/5

I=0.4 amp

Measurement of voltage

Voltage V = ε – Ir

V = 2 – 0.4 × 1

V = 2 – 0.4V
V=1.6 volts

i

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