Quiz — Onde mécanique 2015 2016.pdf

Question 1 sur 10 20:00

[{"id":23179,"question":"Quelle grandeur physique caractérise la hauteur d'un son ?","option_a":"La vitesse","option_b":"La fréquence","option_c":"L'amplitude","option_d":"La longueur d'onde","option_e":"","option_f":"","bonne_reponse":"b","explication":"La fréquence détermine la hauteur du son : plus elle est élevée, plus le son est aigu.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"La vitesse\", \"b\": \"La fréquence\", \"c\": \"L'amplitude\", \"d\": \"La l","_debug_options_count":4},{"id":23180,"question":"Une onde mécanique a une fréquence de 50 Hz et une longueur d'onde de 2 m. Quelle est sa vitesse de propagation ?","option_a":"25 m\/s","option_b":"50 m\/s","option_c":"100 m\/s","option_d":"200 m\/s","option_e":"","option_f":"","bonne_reponse":"c","explication":"La vitesse v = λ × f = 2 m × 50 Hz = 100 m\/s.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"c\", \"options\": {\"a\": \"25 m\/s\", \"b\": \"50 m\/s\", \"c\": \"100 m\/s\", \"d\": \"200 m\/s\"}}","_debug_options_count":4},{"id":23181,"question":"Les ondes sonores sont des ondes transversales.","option_a":"Vrai","option_b":"Faux","option_c":"","option_d":"","option_e":"","option_f":"","bonne_reponse":"b","explication":"Les ondes sonores sont des ondes longitudinales car la vibration se fait dans la même direction que la propagation.","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":23182,"question":"Quelle formule relie la période T et la fréquence f d'une onde ?","option_a":"T = f","option_b":"T = 1\/f","option_c":"T = f²","option_d":"T = √f","option_e":"","option_f":"","bonne_reponse":"b","explication":"La période T est l'inverse de la fréquence : T = 1\/f.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"T = f\", \"b\": \"T = 1\/f\", \"c\": \"T = f²\", \"d\": \"T = √f\"}}","_debug_options_count":4},{"id":23183,"question":"Lorsqu'une onde passe d'un milieu à un autre plus dense, sa vitesse :","option_a":"Augmente","option_b":"Diminue","option_c":"Reste constante","option_d":"Devient nulle","option_e":"","option_f":"","bonne_reponse":"b","explication":"La vitesse d'une onde diminue lorsqu'elle passe dans un milieu plus dense (ex : lumière dans l'eau).","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"Augmente\", \"b\": \"Diminue\", \"c\": \"Reste constante\", \"d\": \"Devient ","_debug_options_count":4},{"id":23184,"question":"Quelle est l'unité SI de la longueur d'onde ?","option_a":"Hertz (Hz)","option_b":"Mètre (m)","option_c":"Seconde (s)","option_d":"Newton (N)","option_e":"","option_f":"","bonne_reponse":"b","explication":"La longueur d'onde s'exprime en mètres (m) dans le système international.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"Hertz (Hz)\", \"b\": \"Mètre (m)\", \"c\": \"Seconde (s)\", \"d\": \"Newton ","_debug_options_count":4},{"id":23185,"question":"Une onde mécanique peut se propager dans le vide.","option_a":"Vrai","option_b":"Faux","option_c":"","option_d":"","option_e":"","option_f":"","bonne_reponse":"b","explication":"Les ondes mécaniques nécessitent un milieu matériel pour se propager (contrairement aux ondes électromagnétiques).","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":23186,"question":"Si la fréquence d'une onde double, que devient sa longueur d'onde (à vitesse constante) ?","option_a":"Elle double","option_b":"Elle reste la même","option_c":"Elle est divisée par deux","option_d":"Elle est multipliée par quatre","option_e":"","option_f":"","bonne_reponse":"c","explication":"Si v = λ × f et v est constante, alors λ = v\/f. Si f double, λ est divisée par deux.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"c\", \"options\": {\"a\": \"Elle double\", \"b\": \"Elle reste la même\", \"c\": \"Elle est divisée","_debug_options_count":4},{"id":23187,"question":"Quelle propriété des ondes est responsable de l'écho ?","option_a":"La diffraction","option_b":"La réflexion","option_c":"La réfraction","option_d":"L'interférence","option_e":"","option_f":"","bonne_reponse":"b","explication":"L'écho est dû à la réflexion des ondes sonores sur une surface.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"La diffraction\", \"b\": \"La réflexion\", \"c\": \"La réfraction\", \"d\"","_debug_options_count":4},{"id":23188,"question":"La superposition de deux ondes de même amplitude et en opposition de phase donne :","option_a":"Une onde de même amplitude","option_b":"Une onde d'amplitude nulle","option_c":"Une onde de fréquence double","option_d":"Une onde de vitesse nulle","option_e":"","option_f":"","bonne_reponse":"b","explication":"En opposition de phase, les amplitudes s'annulent : c'est le phénomène d'interférence destructive.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"Une onde de même amplitude\", \"b\": \"Une onde d'amplitude nulle\", ","_debug_options_count":4}]