Resistance, Resistivity, and Ohm’s Law AP Physics 2 MCQ – Exam Style Questions etc.
Resistance, Resistivity, and Ohm’s Law AP Physics 2 MCQ
Unit 11: Electric Circuits
Weightage : 15–18%
Exam Style Practice Questions ,Resistance, Resistivity, and Ohm's Law AP Physics 2 MCQ
Questions
A circuit contains a length of tungsten wire with resistance R. An increase in the resistance would result if which of the following could be decreased?
(A) The resistivity of the tungsten
(B) The cross-sectional area of the wire
(C) The length of the wire
(D) The temperature of the wire
(E) The current in the wire
▶️Answer/Explanation
Ans: B
(A) The resistivity of the tungsten:
Resistivity (\( \rho \)) is directly proportional to resistance. If resistivity decreases, resistance decreases.
(B) The cross-sectional area of the wire:
Cross-sectional area (\( A \)) is inversely proportional to resistance. If the cross-sectional area decreases, resistance increases.
(C) The length of the wire:
Length (\( L \)) is directly proportional to resistance. If the length decreases, resistance decreases.
(D) The temperature of the wire:
For most conductors, including tungsten, resistance increases with an increase in temperature. So if the temperature decreases, the resistance would also typically decrease.
(E) The current in the wire:
The current (\( I \)) flowing through the wire does not directly affect the resistance in this context. Resistance is a property of the material and its dimensions.
Questions
In the circuit shown above, a student has measured the currents that are given in the diagram, but does not know all the resistance values. The magnitude of the potential difference between points A and B is
(A) 10 V
(B) 20 V
(C) 30 V
(D) 35 V
(E) 40 V
▶️Answer/Explanation
Ans: B
Current in AB is 2 A and resistance across it 10 Ω.
Using Ohm’s law in wire AB.
$V= IR$
$V_{AB}=\text{2 A} \times 10 $
$V_{AB}= \text{20 volt}$
Questions
Two 9 V batteries and three identical \(600\Omega \) resistors are connected in a circuit, as shown above. Neglect internal resistance in the batteries and consider all meters to be ideal. A voltmeter would read 6 V if connected correctly between which two points in the circuit?
(A) a and b
(B) a and f
(C) b and f
(D) c and d
(E) f and g
▶️Answer/Explanation
Ans: E
‘
So in branch g and f current flowing is 0.01A and resistance across it is 600 ohm .
Using Ohms law,
$\begin{aligned} & V=I R \\ & V=0.01 \times 600 \\ & V=6\mathrm{~v}\end{aligned}$
Questions
Two 9 V batteries and three identical \(600\Omega \) resistors are connected in a circuit, as shown above. Neglect internal resistance in the batteries and consider all meters to be ideal. Ammeters are inserted at points I, II, III, and IV. At which of the other points would the ammeter register the same current as the ammeter at point IV ?
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II, and III
▶️Answer/Explanation
Ans:E
Questions
Two 9 V batteries and three identical \(600\Omega \) resistors are connected in a circuit, as shown above. Neglect internal resistance in the batteries and consider all meters to be ideal. What is the total power dissipated in the three
resistors?
(A) 0.023 W
(B) 0.045 W
(C) 0.090 W
(D) 0.36 W
(E) 9.0 W
▶️Answer/Explanation
Ans: C