Latest Post

Explanation:

The assertion is incorrect because when the ciliary muscles contract, the eye lens becomes thicker and more curved to focus on nearby objects. When the ciliary muscles relax, the lens becomes thin.

The reason is correct because ciliary muscles change the curvature of the eye lens and hence control its focal length and power.

Final Conclusion:

Assertion (A) is false, but Reason (R) is true.

Explanation:

When white light passes through a glass prism, different colours bend by different amounts due to their different wavelengths. Red light has the longest wavelength and deviates the least, while violet light has the shortest wavelength and deviates the most. This unequal deviation of colours causes the dispersion of white light.

Final Conclusion:

Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).

Explanation:

The assertion is correct because the wavelength of scattered light depends on the size of the particles causing scattering. Very fine particles scatter light of shorter wavelengths (blue) more effectively, while larger particles scatter all wavelengths nearly equally, making the scattered light appear white.

Final Conclusion:

Assertion (A) is true, but Reason (R) is false.

Evaluation:

• The Assertion (A) is true because nichrome is widely used as a heating element due to its high resistivity and ability to withstand high temperatures.
• The Reason (R) is false because although nichrome has high resistivity, its resistance does not decrease with increase in temperature; instead, it increases slightly like other metallic conductors.

Correct Option:
Assertion is true, but Reason is false.

Evaluation:

• Assertion (A) is true because bending a wire does not change its length, area of cross-section, or material, hence its resistance remains the same.
• Reason (R) is true because resistance depends on the resistivity of the material (R = ρL/A).
• However, Reason (R) is not the correct explanation of Assertion (A), since the assertion is explained by unchanged length and area, not directly by resistivity alone.

Correct Option:
Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.

Evaluation:

• Assertion (A) is true because magnetic field lines represent the direction of the magnetic field at a point.
• Reason (R) is true because a compass needle can show only one definite direction of the magnetic field at a point.
• Reason (R) correctly explains Assertion (A).

Correct Option:
Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

Evaluation:

• Assertion (A) is true because at any point the magnetic field has a unique direction, so field lines cannot cross.
• Reason (R) is true because magnetic field is a vector quantity having both magnitude and direction.
• However, Reason (R) is not the correct explanation of Assertion (A), since the non-intersection is specifically due to the impossibility of having two directions of magnetic field at the same point.

Correct Option:
Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.

Evaluation:

• Assertion (A) is true because a current carrying solenoid produces a magnetic field similar to that of a bar magnet, with distinct north and south poles.
• Reason (R) is false because the magnetic field pattern depends on the shape of the conductor (straight wire, circular loop, solenoid, etc.).

Correct Option:
Assertion is true, but Reason is false.

Evaluation:

• Assertion (A) is true because the earth wire is connected to a metal plate deep inside the earth to provide effective earthing.
• Reason (R) is true because earthing allows leakage current to flow to the ground, keeping the appliance body at earth potential and preventing electric shock.
• Reason (R) correctly explains Assertion (A).

Correct Option:
Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

Evaluation:

• Assertion (A) is false because an electric fuse is always connected in series with the main line so that the entire current of the circuit passes through it.
• Reason (R) is true because when current exceeds the rated value, the fuse wire melts due to heating effect and breaks the circuit.

Correct Option:
Assertion is false, but Reason is true.