The conductivity of a metal decreases with the increase in temperature on account of:
- ADecrease in number density of electrons.
- BDecrease in resistivity.
- CDecrease in relaxation time.
- DIncrease in mean free path.
Question types
Current Electricity question types
606 questions across 7 question groups — pick any mix to generate a Physics paper with step-by-step answer keys.
606
Questions
7
Question groups
5
Question types
01
M.C.Q [1M]
228 Q→02Assertion (A) & Reason (B) MCQ
20 Q→031 Marks Question
59 Q→04Short Answer Type Questions [2M]
93 Q→053 Marks Question
102 Q→06Long Answer Type Questions [5M]
103 Q→07Fill in the blanks.[1M]
1 Q→Sample Questions
Current Electricity questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
Kirchhoff ’s first rule at a junction in an electrical network, deals with conservation of:
- AEnergy.
- BCharge.
- CMomentum.
- DBoth energy and charge.
A potentiometer can measure emf of a cell because:
- AThe sensitivity of potentiometer is large.
- BNo current is drawn from the cell at balance.
- CNo current flows in the wire of potentiometer at balance.
- DInternal resistance of cell is neglected.
Two resistors R1 and R2 of $4\Omega$ and $6\Omega$ are connected in parallel across a battery. The ratio of power dissipated in them, P1 : P2 will be:
- A4 : 9
- B3 : 2
- C9 : 4
- D2 : 3
On increasing the temperature of a conductor, its resistance increases because -
- ARelaxation time increases
- BMass of the electron increases
- ✓Relaxation time decreases
- DMass of the electron decreases
Answer: C.
View full solution →For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
Reason: The current carrying wire attracts the man towards it.
- Both A and R are true, and R is the correct explanation of A.
- Both A and R are true, but R is not the correct explanation of A.
- A is true, but R is false.
- A is false, and R is also false.
Reason: The current carrying wire attracts the man towards it.
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
Reason: A 100 watt bulb has more resistance than a 200W bulb.
- Both A and R are true, and R is the correct explanation of A.
- Both A and R are true, but R is not the correct explanation of A.
- A is true, but R is false.
- A is false, and R is also false.
Reason: A 100 watt bulb has more resistance than a 200W bulb.
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
Reason: Direction of motion of electrons are randomly oriented.
- Both A and R are true, and R is the correct explanation of A.
- Both A and R are true, but R is not the correct explanation of A.
- A is true, but R is false.
- A is false, and R is also false.
Reason: Direction of motion of electrons are randomly oriented.
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
Reason: A current carrying wire should have non-zero charge.
- Both A and R are true, and R is the correct explanation of A.
- Both A and R are true, but R is not the correct explanation of A.
- A is true, but R is false.
- A is false, and R is also false.
Reason: A current carrying wire should have non-zero charge.
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
Reason: Insulator have no free charge carrier.
- Both A and R are true, and R is the correct explanation of A.
- Both A and R are true, but R is not the correct explanation of A.
- A is true, but R is false.
- A is false, and R is also false.
Reason: Insulator have no free charge carrier.
Choose the correct alternative:
Alloys usually have much (lower/ higher) temperature coefficients of resistance than pure metals.
Alloys usually have much (lower/ higher) temperature coefficients of resistance than pure metals.
Choose the correct alternative:
Alloys of metals usually have (greater/ less) resistivity than that of their constituent metals.
Alloys of metals usually have (greater/ less) resistivity than that of their constituent metals.
Answer the following questions:
Is Ohm’s law universally applicable for all conducting elements? If not, give examples of elements which do not obey Ohm’s law.
Is Ohm’s law universally applicable for all conducting elements? If not, give examples of elements which do not obey Ohm’s law.
Choose the correct alternative:
The resistivity of a typical insulator (e.g., amber) is greater than that of a metal by a factor of the order of (1022/103).
The resistivity of a typical insulator (e.g., amber) is greater than that of a metal by a factor of the order of (1022/103).
Choose the correct alternative:
The resistivity of the alloy manganin is nearly independent of/ increases rapidly with increase of temperature.
The resistivity of the alloy manganin is nearly independent of/ increases rapidly with increase of temperature.
Answer the following questions:
A high tension (HT) supply of, say, 6 kV must have a very large internal resistance. Why?
A high tension (HT) supply of, say, 6 kV must have a very large internal resistance. Why?
The storage battery of a car has an emf of 12 V. If the internal resistance of the battery is $0.4\ \Omega,$ what is the maximum current that can be drawn from the battery?
View full solution →A negligibly small current is passed through a wire of length 15m and uniform cross-section $6.0\times10^{-7}\ \text{m}^2,$ and its resistance is measured to be $5.0\ \Omega.$ What is the resistivity of the material at the temperature of the experiment?
View full solution →Figure shows a 2.0 V potentiometer used for the determination of internal resistance of a 1.5 V cell. The balance point of the cell in open circuit is 76.3 cm. When a resistor of $9.5\ \Omega$ is used in the external circuit of the cell, the balance point shifts to 64.8 cm length of the potentiometer wire. Determine the internal resistance of the cell.
View full solution →At room temperature (27.0°C) the resistance of a heating element is $100\ \Omega.$ What is the temperature of the element if the resistance is found to be $117\ \Omega,$ given that the temperature coefficient of the material of the resistor is $1.70\times10^{-4}\ ^\circ\text{C}^{-1}.$
View full solution →A resistance of R draws current from a potentiometer. The potentiometer wire, AB, has a total resistance of Ro. A voltage V is supplied to the potentiometer. Derive an expression for the voltage across R when the sliding contact is in the middle of potentiometer wire.
Given n resistors each of resistance R, how will you combine them to get the (i) maximum (ii) minimum effective resistance? What is the ratio of the maximum to minimum resistance?
A battery of emf 10 V and internal resistance $3\ \Omega$ is connected to a resistor. If the current in the circuit is 0.5 A, what is the resistance of the resistor? What is the terminal voltage of the battery when the circuit is closed?
View full solution →- Three resistors $2\ \Omega,\ 4\ \Omega\ \text{and}\ 5\ \Omega$ are combined in parallel. What is the total resistance of the combination?
- If the combination is connected to a battery of emf 20 V and negligible internal resistance, determine the current through each resistor, and the total current drawn from the battery.
- In a metre bridge [Fig. 3.27], the balance point is found to be at 39.5 cm from the end A, when the resistor Y is of $12.5\ \Omega.$ Determine the resistance of X. Why are the connections between resistors in a Wheatstone or meter bridge made of thick copper strips?
- Determine the balance point of the bridge above if X and Y are interchanged.
- What happens if the galvanometer and cell are interchanged at the balance point of the bridge? Would the galvanometer show any current?
Determine the equivalent resistance of networks shown in Fig.
Figure shows a potentiometer with a cell of 2.0 V and internal resistance $0.04\ \Omega$ maintaining a potential drop across the resistor wire AB. A standard cell which maintains a constant emf of 1.02 V (for very moderate currents upto a few mA) gives a balance point at 67.3 cm length of the wire. To ensure very low currents drawn from the standard cell, a very high resistance of $600\ \text{k}\Omega$ is put in series with it, which is shorted close to the balance point. The standard cell is then replaced by a cell of unknown emf $\varepsilon$ and the balance point found similarly, turns out to be at 82.3 cm length of the wire.
View full solution →- What is the value $\varepsilon?$
- What purpose does the high resistance of $600\ \text{k}\Omega$ have?
- Is the balance point affected by this high resistance?
- Is the balance point affected by the internal resistance of the driver cell?
- Would the method work in the above situation if the driver cell of the potentiometer had an emf of 1.0 V instead of 2.0 V?
- Would the circuit work well for determining an extremely small emf, say of the order of a few mV (such as the typical emf of a thermo-couple)? If not, how will you modify the circuit?
Determine the current in each branch of the network shown in Fig.:
Two wires of equal length, one of aluminium and the other of copper have the same resistance. Which of the two wires is lighter? Hence explain why aluminium wires are preferred for overhead power cables.
$(\rho_{\text{A}1}=2.63\times10^{-8}\Omega\ \text{m,}\ \text{Relative density of Al}=2.7,\ \text{of Cu}=8.9)$
View full solution →$(\rho_{\text{A}1}=2.63\times10^{-8}\Omega\ \text{m,}\ \text{Relative density of Al}=2.7,\ \text{of Cu}=8.9)$
Given the resistances of $1\ \Omega,\ 2\ \Omega,\ 3\ \Omega,$ how will be combine them to get an equivalent resistance of,
View full solution →- $(11/3)\ \Omega$
- $(11/5)\ \Omega$
- $6\ \Omega$
- $(6/11)\ \Omega?$
The value of e. m. f. is does not depend on the ____________ of the circuit.
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