Question: what factors determine the amount of torque on the armature of a rotating dc electric motor
[{'answer': 'separately excited field', 'provenance': [{'wikipedia_id': '10004115', 'title': 'Brushed DC electric motor', 'start_paragraph_id': 46, 'start_character': 103, 'end_paragraph_id': 46, 'end_character': 127, 'bleu_score': 1.0, 'section': 'Section::::Torque and speed of a DC motor.\n'}]}, {'answer': 'self - excited field', 'provenance': [{'wikipedia_id': '10004115', 'title': 'Brushed DC electric motor', 'start_paragraph_id': 46, 'start_character': 129, 'end_paragraph_id': 46, 'end_character': 150, 'bleu_score': 1.0, 'section': 'Section::::Torque and speed of a DC motor.\n'}]}, {'answer': 'permanent - field', 'provenance': [{'wikipedia_id': '10004115', 'title': 'Brushed DC electric motor', 'start_paragraph_id': 46, 'start_character': 151, 'end_paragraph_id': 46, 'end_character': 167, 'bleu_score': 1.0, 'section': 'Section::::Torque and speed of a DC motor.\n'}]}, {'provenance': [{'wikipedia_id': '10004115', 'title': 'Brushed DC electric motor', 'start_paragraph_id': 46, 'start_character': 0, 'end_paragraph_id': 46, 'end_character': 341, 'bleu_score': 0.962600167205617, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9355551978193774728}, 'section': 'Section::::Torque and speed of a DC motor.\n'}]}]