Two waves interfering at a point have a path difference of lambda / 2. Their corresponding phase difference is exactly: MCQ with Answer and Explanation

Explanation:
J. J. Thomson discovered the electron in 1897 through cathode ray tube experiments, measuring charge-to-mass ratio (e/m) of cathode rays. Proton: Rutherford; neutron: Chadwick; nucleus: Rutherford's gold foil experiment. Memory aid: 'Thomson = plum pudding model (electrons in positive sphere)'. This historical question tests knowledge of subatomic particle discoveries, frequently examined in competitive exams. Always recall the experimental methods: Thomson (cathode rays), Millikan (oil drop for e), Rutherford (alpha scattering).

Explanation:
Escape velocity v_e = √(2GM/R), where M is planet mass, R its radius. Thus v_e depends on both M and R. It is independent of the escaping body's mass (as gravitational and inertial mass cancel). Memory tip: 'v_e ∝ √(M/R); larger M or smaller R ⇒ higher escape velocity'. This gravitation formula application is frequently tested in competitive exams. Always recall that escape velocity is a property of the planet, not the projectile. This problem assesses understanding of gravitational potential energy concepts.

Explanation:
For perpendicular forces: R = √(F₁² + F₂²) = √(9 + 16) = √25 = 5 N. Pythagorean theorem applies for vector addition at 90°. Memory aid: '3-4-5 triangle for perpendicular forces'. Basic vector addition problem testing magnitude calculation, common in mechanics sections of competitive exams.