Q1:
Question for Assertion & Reason Type Questions: Electricity
Try yourself:Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:
Assertion : Silver is not used to make electric wires.
Reason : Silver is a bad conductor.
Explanation
- Assertion (A) states that "Silver is not used to make electric wires," which is true because silver is rarely used for this purpose due to its high cost.
- Reason (R) claims "Silver is a bad conductor," which is false; in fact, silver is the best conductor of electricity.
- Therefore, the correct choice is option 3: Assertion (A) is true but reason (R) is false.
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Q2:
Question for Assertion & Reason Type Questions: Electricity
Try yourself: Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:Assertion : When the resistances are connected end- to-end consecutively, they are said to be in series.
Reason : In case the total resistance is to be increased, then the individual resistances are connected in series.
Explanation
- Current in a circuit depends on resistance as well as Potential Difference of the circuit.
- It is necessary to combine two or more resistances to get the required current in the electrical circuits
- Resistances can be combined in two ways: in series and in parallel.
- When two or more resistances are connected end to end consecutively, they are said to be connected in series.
- And on the other hand, when two or more resistances are connected between the same two points, they are said to be connected in parallel.
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Q3:
Question for Assertion & Reason Type Questions: Electricity
Try yourself: Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:Assertion: Tungsten metal is used for making filaments of incandescent lamps.
Reason : The melting point of tungsten is very low.
Explanation
Tungsten is selected for making filaments of incandescent lamp bulbs because tungsten can sustain high temperature and it has a high melting point, with high resistivity.
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Q4:
Question for Assertion & Reason Type Questions: Electricity
Try yourself: Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:Assertion : Alloys are commonly used in electrical heating devices, like electrical iron, toasters etc.
Reason : Alloys do not oxidise (burn) readily at high temperatures.
Explanation
An alloy generally has a higher resistivity than its constituent metals. Alloys do not oxidise (burn) readily at high temperatures. For this reason, they are commonly used in electrical heating devices, like electric iron, toasters etc.
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Q5:
Q6:
Question for Assertion & Reason Type Questions: Electricity
Try yourself: Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:Assertion : When the resistances are connected between the same two points, they are said to be connected in parallel.
Reason : In case the resistance is to be decreased, then the individual resistances are connected in parallel.
Explanation
In parallel connection, all the elements are connected between the same two points hence the voltage drop across any number of resistors or other elements connected in parallel is the same.
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Q7:
Q8:
Question for Assertion & Reason Type Questions: Electricity
Try yourself: Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:Assertion : The electric bulbs glow immediately when the switch is on.
Reason : The drift velocity of electrons in a metallic wire is very high.
Explanation
In a conductor there are large numbers of free electrons. When we close the circuit, the electric field is established instantly with the speed of electromagnetic waves which causes electron drift at every portion of the circuit. Due to which the current is set up in the entire circuit instantly. The current which is set up does not wait for the electrons to flow from one end of the conductor to another end. Due to this, the bulb glows immediately when the switch is on.
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Q9:
Q10:
Question for Assertion & Reason Type Questions: Electricity
Try yourself: Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:Assertion : Insulators do not allow flow of current through themselves.
Reason : They have no free-charge carriers.
Explanation
Insulators are bad conductors because they don't have free charge carriers which will flow and hence the correct option becomes A.
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Q11:
Question for Assertion & Reason Type Questions: Electricity
Try yourself:Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:
Assertion : The equation V = RI does not apply to those conducting devices which do not obey Ohm’s law.
Reason : V= RI is mathematical representation of Ohm’s law.
Explanation
- The assertion states that the equation V = RI does not apply to devices not obeying Ohm's law. This is true because Ohm's law describes a linear relationship between voltage, current, and resistance.
- The reason states that V = RI is the mathematical representation of Ohm's law. This is also true, as Ohm's law is represented by this equation.
- While both statements are true, the reason does not directly explain why the equation doesn't apply to non-ohmic devices, making the correct choice B.
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Q12:
Question for Assertion & Reason Type Questions: Electricity
Try yourself:Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:
Assertion : Heater wire must have high resistance and high melting point.
Reason : If resistance is high, the electric conductivity will be less.
Explanation
Heater wire must have high resistance and high melting point because, according to Joule’s law (H = I²Rt), heat produced is high if resistance is high. The wire needs a high melting point to ensure it does not melt with the increase in temperature. While the reason states that high resistance results in lower conductivity, it does not explain why a high melting point is necessary for the operation of a heater wire.
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Q13:
Q14:
Question for Assertion & Reason Type Questions: Electricity
Try yourself:Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:
Assertion: Bending a wire does not affect electrical resistance.
Reason: The resistance of a wire is only proportional to the resistivity of the material, the length of the wire and the area of cross-section of the wire.
Explanation
Resistance of wire R = 
Where p is the resistivity of the material, l is the length and A is the area of cross-section of the wire. Since when a wire is bent, resistivity, length and area of cross-section do not change; therefore, resistance of the wire also remains the same.
Therefore, both A and R are correct, and R is the correct explanation of A.
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Q15:
Question for Assertion & Reason Type Questions: Electricity
Try yourself: Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:Assertion : If a graph is plotted between the potential difference and the current flowing, the graph is a straight line passing through the origin.
Reason : The current is directly proportional to the potential difference.
Explanation
According to Ohm's law, the potential difference across a conductor is directly proportional to the current through it.
V=IR
Hence the curve is a straight line passing through the origin.
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