题目1单选题
在磁感应强度为 <img src="https://tihai-oss-cloud.itihey.com/img/b64faf1afb5e7b08f2ae9f2ba33efa17.png"><img src="https://tihai-oss-cloud.itihey.com/img/ec50f767f0337d95454a612c7a0de4e8.png">A. <img src="https://tihai-oss-cloud.itihey.com/img/aab75d9328acb61c57061fe0e0a57b23.png">B. <img src="https://tihai-oss-cloud.itihey.com/img/60b9ead6e3512d677ccd85da58a178c3.webp">C. <img src="https://tihai-oss-cloud.itihey.com/img/7d9ebcef39fa2f06cf6ce26cd94e6aa8.webp">D. <img src="https://tihai-oss-cloud.itihey.com/img/c121f87715183d8bf8cb96a2889b5e01.webp">