The force between two charges in vacuum is F. If a medium of dielectric constant 4 is introduced, force becomes MCQ with Answer and Explanation

Explanation:
The volume of a sphere is given by V = (4/3)πr³. The formula for relative error in volume is (ΔV/V) = 3 × (Δr/r). Since the percentage error in radius (Δr/r × 100) is 2%, the percentage error in volume will be 3 × 2% = 6%. Constants like 4/3 and π do not contribute to the error.

Explanation:
Dispersion happens because refractive index varies with wavelength. Prism, rainbow. Scattering is Tyndall effect (blue sky). Polarisation restricts vibrations.

Explanation:
Reading 0.250 cm has three significant figures (2,5, and trailing zero after decimal). Least count gives precision, trailing zero indicates measurement to 0.001 cm, so it's significant.