Heat transfer in vacuum occurs by MCQ with Answer and Explanation

Explanation:
β⁻ decay: n → p + e⁻, so A unchanged, Z increases by 1.

Explanation:
Generator converts mechanical energy (rotation) to electrical energy via electromagnetic induction. Motor does the reverse (electrical to mechanical). Transformer changes AC voltage levels; galvanometer detects small currents. Memory aid: 'Generator: motion ⇒ electricity; Motor: electricity ⇒ motion'. This principle-based question tests understanding of energy conversion devices, crucial for electromagnetism in competitive exams. Always link device function to underlying physics law: generator (Faraday's law), motor (Lorentz force).

Explanation:
Pressure has dimensions [ML⁻¹T⁻²]. Energy per unit volume: Energy is [ML²T⁻²], volume is [L³], so [ML²T⁻²]/[L³] = [ML⁻¹T⁻²], matching pressure. Force per unit length is [MLT⁻²]/[L] = [MT⁻²]. Momentum per unit area is [MLT⁻¹]/[L²] = [ML⁻¹T⁻¹]. Power per unit volume is [ML²T⁻³]/[L³] = [ML⁻¹T⁻³]. This dimensional equivalence explains why pressure appears in Bernoulli's equation alongside energy density. Memory aid: Pressure and energy density both represent stored energy per spatial dimension.