ROUTERA

Electricity

Class 10th Science Chapter Assertion and Reason

Electricity

  • Options:
    a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
    b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
    c) Assertion (A) is true, but Reason (R) is false.
    d) Assertion (A) is false, but Reason (R) is true.

Question 1

Assertion (A): Electric current is the flow of electric charge.
Reason (R): The flow of electrons constitutes the electric current in a circuit.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Electric current is defined as the flow of electric charge, primarily through the movement of electrons in a conductor.

Question 2

Assertion (A): The unit of electric current is the ampere.
Reason (R): An ampere is defined as one coulomb of charge flowing through a conductor in one second.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: The ampere (A) is indeed defined as the flow of one coulomb of charge per second, indicating the strength of the electric current.

Question 3

Assertion (A): Voltage is the potential difference between two points in an electric circuit.
Reason (R): Voltage causes current to flow in a circuit.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Voltage (or potential difference) between two points provides the necessary force to push electric charges through a circuit, thereby causing current to flow.

Question 4

Assertion (A): Ohm’s law states that the current flowing through a conductor is directly proportional to the voltage across it.
Reason (R): Ohm’s law applies only to conductors that have a constant resistance.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Ohm's law is valid only for ohmic materials where resistance remains constant, allowing for a linear relationship between voltage and current.

Question 5

Assertion (A): A series circuit has the same current flowing through all components.
Reason (R): In a series circuit, components are connected end-to-end, creating a single path for current.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: In a series circuit, since the components are connected in a single path, the same current flows through each component without branching.

Question 6

Assertion (A): In a parallel circuit, the total current is equal to the sum of the currents through each branch.
Reason (R): Each branch in a parallel circuit has the same voltage across it.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: In a parallel circuit, the voltage across each branch is the same, leading to the total current being the sum of the individual branch currents.

Question 7

Assertion (A): An increase in resistance in a circuit will decrease the current flow.
Reason (R): According to Ohm's law, current is inversely proportional to resistance when voltage is constant.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Ohm's law states I=VRI = \frac{V}{R}, showing that an increase in resistance leads to a decrease in current, provided the voltage remains constant.

Question 8

Assertion (A): Insulators are materials that allow electric current to flow easily through them.
Reason (R): Insulators have high resistance.

  • Answer: b) Assertion (A) is false, but Reason (R) is true.
  • Explanation: Insulators do not allow electric current to flow easily; they are characterized by high resistance, which prevents current flow.

Question 9

Assertion (A): Electric power is the rate at which electrical energy is consumed or converted.
Reason (R): Power is calculated by multiplying voltage and current.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Electric power PP is calculated using the formula P=V×IP = V \times I, indicating how much electrical energy is consumed over time.

Question 10

Assertion (A): A short circuit occurs when a low-resistance path is created.
Reason (R): Short circuits can lead to excessive current flow, potentially causing fires.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: A short circuit provides an unintended low-resistance pathway, resulting in a surge of current that can generate heat and cause fires.

Question 11

Assertion (A): A fuse is used to protect electrical circuits from overload.
Reason (R): A fuse melts and breaks the circuit when excessive current flows.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Fuses are designed to melt and disconnect the circuit when the current exceeds a certain threshold, preventing damage to appliances and wiring.

Question 12

Assertion (A): Electric energy can be converted to other forms of energy.
Reason (R): Electric energy is versatile and can power various devices, such as heaters and motors.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Electric energy can be transformed into heat, light, mechanical energy, and other forms, making it highly versatile for different applications.

Question 13

Assertion (A): The resistance of a conductor decreases with an increase in temperature.
Reason (R): Increased temperature causes more collisions among charge carriers, increasing resistance.

  • Answer: b) Assertion (A) is false, but Reason (R) is true.
  • Explanation: The resistance of most conductors actually increases with temperature due to more frequent collisions among charge carriers as they gain kinetic energy.

Question 14

Assertion (A): Direct current (DC) flows in one direction only.
Reason (R): Alternating current (AC) changes direction periodically.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: DC provides a constant flow of electric charge in one direction, while AC reverses direction at regular intervals, which is essential for powering homes and businesses.

Question 15

Assertion (A): A voltmeter is used to measure current in a circuit.
Reason (R): A voltmeter is connected in series with the circuit.

  • Answer: b) Assertion (A) is false, but Reason (R) is true.
  • Explanation: A voltmeter measures voltage and is connected in parallel with the circuit, not in series, to accurately measure the potential difference across components.

Question 16

Assertion (A): Conductors have free electrons that allow for easy current flow.
Reason (R): Insulators lack free electrons, which makes them unable to conduct electricity.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Conductors have free-moving electrons that facilitate the flow of electric current, while insulators have tightly bound electrons, restricting current flow.

Question 17

Assertion (A): The total resistance in a series circuit is the sum of individual resistances.
Reason (R): This is because the same current flows through each resistor in a series circuit.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: In a series circuit, since the current is the same through all components, the total resistance is simply the sum of the individual resistances.

Question 18

Assertion (A): The flow of electric current produces heat in a conductor.
Reason (R): This is due to the collisions between moving electrons and the fixed particles in the conductor.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: When electric current flows through a conductor, electrons collide with the atoms in the conductor, generating heat due to the energy lost during these collisions.

Question 19

Assertion (A): A rheostat can be used to control the current in a circuit.
Reason (R): A rheostat works by varying its resistance.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: A rheostat allows adjustment of resistance in a circuit, which in turn controls the current flowing through the circuit according to Ohm's law.

Question 20

Assertion (A): The electric field strength is directly proportional to the voltage.
Reason (R): The electric field strength is inversely proportional to the distance from the charge.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: The electric field strength EE is defined as E=VdE = \frac{V}{d}, where VV is voltage and dd is distance. Thus, an increase in voltage increases the electric field strength, while the field strength decreases as the distance from the charge increases.