The device used to convert solar energy into electrical energy is MCQ with Answer and Explanation

Explanation:
Law of conservation of energy states total energy (all forms) is conserved in isolated systems. For mechanical energy (KE + PE) to be conserved, only conservative forces (like gravity, spring) must act; non-conservative forces (friction) convert mechanical energy to heat. Option C precisely states this condition. Options A and B are incorrect as KE and PE individually vary. Option D is false as thermal energy can exist. Memory tip: 'Mechanical energy conserved ⇔ no non-conservative work'. This nuanced understanding is critical for energy problems in competitive exams, where distractors often omit the conservative force condition.

Explanation:
At C (centre of curvature), image is at C, real, inverted, same size. At F, image at infinity. Beyond C, between F and C, diminished. Object between F and C gives beyond C, enlarged.

Explanation:
Potential difference V = W/q: work per unit charge. Electric field E = F/q: force per unit charge. Memory tip: 'Potential = work/charge (scalar); Field = force/charge (vector)'. Electrostatics definition frequently tested in competitive exams.