This term we have a new teacher of English. His name is Mr. Peterson. He is an Australian. He is not very tall and he is thin. He has a round face and small blue eyes. He wears glasses and they make him look smart. He has dark brown hair.

      Mr. Peterson works very hard. In class, he has many good ideas to make the class very interesting. We all like his class. After class, he always encourages us to speak more English. Sometimes, he plays games with us. He is very strong and he can play basketball and football very well. He is good at sports. Sometimes he plays table tennis with us, but he doesn’t play it very well.

       Mr. Peterson loves living in China very much. He enjoys lots of things in China. He really loves eating Chinese food. He loves traveling in China too. He is going to visit Xi’an next month.

下列对植物激素的叙述中，错误的是：

某同学在课外研究性学习中发现，一些不能用做电源使用的旧干电池仍然存在较大的电压。他从网上查询得知，是因为旧干电池的内部本身存在较大的电阻（简称内阻），其状况相当于1节干电池与1个电阻R_X串联，电池符号可用如图所示的方式进行表示。
现有以下实验器材，要想测出一节旧干电池的内阻，请你根据实验需要选择合适的实验器材，完成实验任务。
实验器材：旧干电池1节（电压大约在1.0V～1.2V之间，内阻大约在2Ω～3Ω之间）；电流表1只（量程0～0.6A，0～3A）；电阻4个，分别为R₁ =2Ω、R₂ =3Ω、R₃ =100Ω、R₄ = 150Ω；开关2个，导线若干，回答下面问题：

如图，在菱形ABCD中，对角线AC与BD相交于点O，AC=8，BD=6，OE⊥BC，垂足为点E，则OE= ____．