资源简介

【实验指导】新版教科版小学科学四年级下册2.7电路中的开关
实验：做个小开关
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489862&idx=2&sn=3bf254763f8919f84a8250187e5d7f1f&chksm=ebe3bf34dc9436225e6b798afa71eaade28623958896173fc4c15a86fa07fc77792bd84de053&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
实验材料：橡皮、图钉和回形针
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489862&idx=2&sn=3bf254763f8919f84a8250187e5d7f1f&chksm=ebe3bf34dc9436225e6b798afa71eaade28623958896173fc4c15a86fa07fc77792bd84de053&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
实验方法：
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489862&idx=2&sn=3bf254763f8919f84a8250187e5d7f1f&chksm=ebe3bf34dc9436225e6b798afa71eaade28623958896173fc4c15a86fa07fc77792bd84de053&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
1、把回形针伸开放在橡皮上，用?笔在伸开的回形针两端各描一个点作为标记。
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489862&idx=2&sn=3bf254763f8919f84a8250187e5d7f1f&chksm=ebe3bf34dc9436225e6b798afa71eaade28623958896173fc4c15a86fa07fc77792bd84de053&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
2、先把一枚图钉固定在橡皮的一个描点上，再用图钉把回形针大的一端固定在橡皮的另外一个描点上。
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489862&idx=2&sn=3bf254763f8919f84a8250187e5d7f1f&chksm=ebe3bf34dc9436225e6b798afa71eaade28623958896173fc4c15a86fa07fc77792bd84de053&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
3、把橡皮回形针开关连接到电路中，看看它能不能控制小灯泡的亮与不亮。
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489862&idx=2&sn=3bf254763f8919f84a8250187e5d7f1f&chksm=ebe3bf34dc9436225e6b798afa71eaade28623958896173fc4c15a86fa07fc77792bd84de053&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
实验结论：我们在设计制作小开关的过程中，不仅需要使用绝缘体材料，
还需要使用导体材料，导体负责接通电路，绝缘体负责断开电路。
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489862&idx=2&sn=3bf254763f8919f84a8250187e5d7f1f&chksm=ebe3bf34dc9436225e6b798afa71eaade28623958896173fc4c15a86fa07fc77792bd84de053&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
理解与应用
1.不要用湿布擦，也不能用湿手触摸电器和开关。
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
2.我们要好好保护绝缘体。
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
3.开关是控制电流通断的。开关必须用导体和绝缘体两种材料组成，开关的种类非常多，有门铃开关，闸刀开关、电扇开关、电灯开关等。
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
4.电路中的开关（又叫电键）起控制电路
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)通和断的作用。一个开关中，塑料是绝缘体，金属是导体。
精炼反馈
1.下列材料能制成小开关的是(?
?
?
?)。
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
A.干木块和铁丝
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
B.铁丝和回形针
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
C.铁片和相片
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
【答案】A
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
【详解】开关需要的材料有导体做的连接器以及绝缘体做的底座，所以需要的材料就是导体和绝緣体的组合。对选项进行分析，就是A选项的干木块与铁丝符合选项。
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
2.下列属于非接触式开关的是(?
?
?
?
)。
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
A.遥控开关
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
B.墙上的电灯开关
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
C.按键开关
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
【答案】A
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)
【详解】根据对选项的分析，可知遥控开关属于非接触式的开关。而墙上的电灯开关和按键开关都是接触式开关。所以题目的答案是A选项。
(?http:?/??/?mp.weixin.?/?s?__biz=MzI4NjA0NDk1Nw==&mid=2247489031&idx=1&sn=5fab1bb7a32246385cd16171b0ef5073&chksm=ebe3b075dc94396395a58721cf9f64e01251a7b12c3440c7753f5707ab4fc4621cc2569f09aa&scene=21"
\l
"wechat_redirect"
\t
"https:?/??/?mp.weixin.?/?_blank?)

展开更多......

收起↑