The primary colours of light are MCQ with Answer and Explanation

Explanation:
R ∝ L² (volume constant). L'=3L => R' = 3² × 6 = 9×6 = 54 Ω. Generally, R' = n² R for stretching n times. Important concept.

Explanation:
Nucleus: protons (+) and neutrons (neutral); electrons orbit outside. Atomic number = proton count; mass number = protons + neutrons. Memory tip: 'Nucleus = nucleons (p+n); electrons in shells'. Basic atomic structure frequently tested in competitive modern physics sections.

Explanation:
Volume constant: A' = A/2 when L' = 2L. R' = ρ(2L)/(A/2) = 4ρL/A = 4R. Memory tip: 'Stretch wire: R ∝ L² when volume fixed'. Resistance proportionality frequently tested in competitive exams.