Quiz — correction exercice 1 pH2+rq forcee elec devoire.pdf

Question 1 sur 10 20:00

[{"id":19259,"question":"Quel est le pH d’une solution dont la concentration en ions H₃O⁺ est de 10⁻⁴ mol\/L ?","option_a":"A. 2","option_b":"B. 4","option_c":"C. 6","option_d":"D. 8","option_e":"","option_f":"","bonne_reponse":"b","explication":"Le pH se calcule par la formule pH = -log[H₃O⁺]. Ici, pH = -log(10⁻⁴) = 4.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"A. 2\", \"b\": \"B. 4\", \"c\": \"C. 6\", \"d\": \"D. 8\"}}","_debug_options_count":4},{"id":19260,"question":"La loi d’Ohm s’applique uniquement aux conducteurs ohmiques.","option_a":"Vrai","option_b":"Faux","option_c":"","option_d":"","option_e":"","option_f":"","bonne_reponse":"a","explication":"La loi d’Ohm (U = R·I) s’applique aux dipôles linéaires passifs, mais pas aux générateurs ou aux dipôles non linéaires comme les diodes.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"Vrai\", \"b\": \"Faux\", \"c\": \"\", \"d\": \"\"}}","_debug_options_count":4},{"id":19261,"question":"Quelle est l’unité de la constante de force électrique k dans la loi de Coulomb (F = k·|q₁q₂|\/r²) ?","option_a":"A. N·m²\/C²","option_b":"B. N\/C","option_c":"C. C\/N","option_d":"D. N·m\/C","option_e":"","option_f":"","bonne_reponse":"a","explication":"L’unité de k est N·m²\/C², car F est en newtons (N), q₁ et q₂ en coulombs (C), et r en mètres (m).","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"A. N·m²\/C²\", \"b\": \"B. N\/C\", \"c\": \"C. C\/N\", \"d\": \"D. N·m\/C\"}}","_debug_options_count":4},{"id":19262,"question":"Un circuit électrique contient une résistance de 100 Ω et une tension de 5 V. Quelle est l’intensité du courant ?","option_a":"A. 0,05 A","option_b":"B. 5 A","option_c":"C. 50 A","option_d":"D. 0,5 A","option_e":"","option_f":"","bonne_reponse":"a","explication":"L’intensité se calcule par I = U\/R = 5\/100 = 0,05 A (loi d’Ohm).","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"A. 0,05 A\", \"b\": \"B. 5 A\", \"c\": \"C. 50 A\", \"d\": \"D. 0,5 A\"}}","_debug_options_count":4},{"id":19263,"question":"Le pH d’une solution augmente lorsque la concentration en ions H₃O⁺ diminue.","option_a":"Vrai","option_b":"Faux","option_c":"","option_d":"","option_e":"","option_f":"","bonne_reponse":"a","explication":"Le pH est inversement proportionnel à [H₃O⁺]. Si [H₃O⁺] diminue, le pH augmente (solution moins acide).","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"Vrai\", \"b\": \"Faux\", \"c\": \"\", \"d\": \"\"}}","_debug_options_count":4},{"id":19264,"question":"Quelle est la puissance dissipée par une résistance de 20 Ω traversée par un courant de 0,5 A ?","option_a":"A. 5 W","option_b":"B. 10 W","option_c":"C. 20 W","option_d":"D. 50 W","option_e":"","option_f":"","bonne_reponse":"b","explication":"La puissance se calcule par P = R·I² = 20 × (0,5)² = 5 W.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"A. 5 W\", \"b\": \"B. 10 W\", \"c\": \"C. 20 W\", \"d\": \"D. 50 W\"}}","_debug_options_count":4},{"id":19265,"question":"Dans un circuit en série, la tension aux bornes de chaque dipôle est égale à la tension totale du générateur.","option_a":"Vrai","option_b":"Faux","option_c":"","option_d":"","option_e":"","option_f":"","bonne_reponse":"b","explication":"Dans un circuit en série, la tension totale est la somme des tensions aux bornes de chaque dipôle (loi des mailles).","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"Vrai\", \"b\": \"Faux\", \"c\": \"\", \"d\": \"\"}}","_debug_options_count":4},{"id":19266,"question":"Quelle est la valeur du pH d’une solution neutre à 25°C ?","option_a":"A. 0","option_b":"B. 7","option_c":"C. 10","option_d":"D. 14","option_e":"","option_f":"","bonne_reponse":"b","explication":"À 25°C, une solution neutre a un pH de 7, car [H₃O⁺] = [HO⁻] = 10⁻⁷ mol\/L.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"A. 0\", \"b\": \"B. 7\", \"c\": \"C. 10\", \"d\": \"D. 14\"}}","_debug_options_count":4},{"id":19267,"question":"La force électrique entre deux charges de 1 µC chacune, séparées de 1 cm, est de :","option_a":"A. 9 × 10⁻³ N","option_b":"B. 9 × 10⁻¹ N","option_c":"C. 9 × 10⁻⁵ N","option_d":"D. 9 × 10⁻⁷ N","option_e":"","option_f":"","bonne_reponse":"b","explication":"F = k·|q₁q₂|\/r² = 9×10⁹ × (10⁻⁶)² \/ (10⁻²)² = 9×10⁻¹ N.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"A. 9 × 10⁻³ N\", \"b\": \"B. 9 × 10⁻¹ N\", \"c\": \"C. 9 × 10⁻","_debug_options_count":4},{"id":19268,"question":"L’énergie électrique consommée par un appareil dépend uniquement de sa puissance.","option_a":"Vrai","option_b":"Faux","option_c":"","option_d":"","option_e":"","option_f":"","bonne_reponse":"b","explication":"L’énergie dépend aussi de la durée d’utilisation (E = P·Δt). Une puissance élevée ne garantit pas une consommation élevée si le temps est court.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"Vrai\", \"b\": \"Faux\", \"c\": \"\", \"d\": \"\"}}","_debug_options_count":4}]