Redraw the circuit of Question 1, putting in an ammeter to measure the current through the resistors and a voltmeter to measure the potential difference across the 12 Ω resistor. What would be the readings in the ammeter and the voltmeter?

Question 2 Page 213 Redraw the circuit of Question 1, putting in an ammeter to measure the current through the resistors and a voltmeter to measure the potential difference across the 12 Ω resistor. What would be the readings in the ammeter and the voltmeter?
The ammeter shows the amount of current in the circuit
The voltmeter shows the amount of voltage (potential difference) across 12 Ω resistor
Hence, we need to find
Current in the circuit (I)
Potential Difference across 12 Ω resistor (V)
Finding current in the circuit
Here,
Potential difference across circuit = 2 + 2 + 2
= 6 V
(Because 3 cells of 2V each)
Since the resistors are in series
We find the equivalent resistance
R = R1 + R2 + R3
R = 5 Ω + 8 Ω + 12 Ω
R = 25 Ω
By Ohm’s law,
V = I R
𝑉/𝑅 = I
I = 𝑉/𝑅
I = 6/25 A
I = 0.24 A
Finding potential difference across 12 Ω resistor
In series combination, current flowing
through all resistors is same
∴ I = 6/25 A
R = 12 Ω
By Ohm’s law,
V = I R
V = 6/25 × 12
V = 72/25
V = 2.88 V
Therefore, Reading shown by
Ammeter is 0.24 A
Voltmeter is 2.88 V

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.