一、彈簧秤的原理

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利(li)用(yong)(yong)彈(dan)(dan)(dan)(dan)簧(huang)(huang)在(zai)被(bei)(bei)(bei)測(ce)(ce)物(wu)(wu)重(zhong)(zhong)(zhong)(zhong)力(li)(li)作(zuo)用(yong)(yong)下(xia)的(de)(de)(de)變(bian)形來(lai)測(ce)(ce)定(ding)該物(wu)(wu)質量的(de)(de)(de)衡器。彈(dan)(dan)(dan)(dan)簧(huang)(huang)具有受(shou)力(li)(li)后(hou)產(chan)生(sheng)與(yu)外力(li)(li)相應的(de)(de)(de)變(bian)形的(de)(de)(de)特性(xing)(xing)。根據胡克(ke)(ke)定(ding)律，彈(dan)(dan)(dan)(dan)簧(huang)(huang)在(zai)彈(dan)(dan)(dan)(dan)性(xing)(xing)極(ji)限內的(de)(de)(de)變(bian)形量與(yu)所受(shou)力(li)(li)的(de)(de)(de)大小成(cheng)正比。稱(cheng)(cheng)重(zhong)(zhong)(zhong)(zhong)時，彈(dan)(dan)(dan)(dan)簧(huang)(huang)變(bian)形所產(chan)生(sheng)的(de)(de)(de)彈(dan)(dan)(dan)(dan)性(xing)(xing)力(li)(li)與(yu)被(bei)(bei)(bei)測(ce)(ce)物(wu)(wu)的(de)(de)(de)重(zhong)(zhong)(zhong)(zhong)量(重(zhong)(zhong)(zhong)(zhong)力(li)(li))相平衡，故從變(bian)形量的(de)(de)(de)大小即可測(ce)(ce)得被(bei)(bei)(bei)測(ce)(ce)物(wu)(wu)的(de)(de)(de)重(zhong)(zhong)(zhong)(zhong)量,進而(er)(er)確定(ding)其(qi)(qi)質量。彈(dan)(dan)(dan)(dan)簧(huang)(huang)秤的(de)(de)(de)稱(cheng)(cheng)量可從1毫克(ke)(ke)到(dao)數十噸。其(qi)(qi)中(zhong)，載荷在(zai)2mg以(yi)下(xia)的(de)(de)(de)，采(cai)(cai)用(yong)(yong)石英(ying)絲彈(dan)(dan)(dan)(dan)簧(huang)(huang)；載荷在(zai)5g以(yi)下(xia)的(de)(de)(de)，采(cai)(cai)用(yong)(yong)平卷(juan)彈(dan)(dan)(dan)(dan)簧(huang)(huang)；載荷量更(geng)大的(de)(de)(de)，采(cai)(cai)用(yong)(yong)螺(luo)(luo)旋(xuan)彈(dan)(dan)(dan)(dan)簧(huang)(huang)和盤形彈(dan)(dan)(dan)(dan)簧(huang)(huang)。常見的(de)(de)(de)彈(dan)(dan)(dan)(dan)簧(huang)(huang)秤是使用(yong)(yong)螺(luo)(luo)旋(xuan)彈(dan)(dan)(dan)(dan)簧(huang)(huang)制成(cheng)的(de)(de)(de)彈(dan)(dan)(dan)(dan)簧(huang)(huang)案秤。在(zai)被(bei)(bei)(bei)測(ce)(ce)物(wu)(wu)放入(ru)秤盤后(hou)，螺(luo)(luo)旋(xuan)彈(dan)(dan)(dan)(dan)簧(huang)(huang)在(zai)被(bei)(bei)(bei)測(ce)(ce)物(wu)(wu)重(zhong)(zhong)(zhong)(zhong)力(li)(li)作(zuo)用(yong)(yong)下(xia)被(bei)(bei)(bei)拉(la)伸(shen)，拉(la)伸(shen)時通過(guo)杠桿裝(zhuang)置使齒條作(zuo)直線運動而(er)(er)帶動齒輪指(zhi)針軸旋(xuan)轉。當彈(dan)(dan)(dan)(dan)簧(huang)(huang)被(bei)(bei)(bei)拉(la)伸(shen)產(chan)生(sheng)的(de)(de)(de)彈(dan)(dan)(dan)(dan)性(xing)(xing)力(li)(li)與(yu)被(bei)(bei)(bei)測(ce)(ce)物(wu)(wu)重(zhong)(zhong)(zhong)(zhong)力(li)(li)平衡時，指(zhi)針就(jiu)在(zai)刻度(du)盤上指(zhi)示(shi)被(bei)(bei)(bei)測(ce)(ce)物(wu)(wu)的(de)(de)(de)重(zhong)(zhong)(zhong)(zhong)量值。彈(dan)(dan)(dan)(dan)簧(huang)(huang)秤具有結(jie)構簡單、讀(du)數直觀的(de)(de)(de)優點。但因彈(dan)(dan)(dan)(dan)簧(huang)(huang)具有彈(dan)(dan)(dan)(dan)性(xing)(xing)滯后(hou)的(de)(de)(de)特性(xing)(xing)，且易受(shou)溫度(du)等外界條件變(bian)化的(de)(de)(de)影響，故其(qi)(qi)準確度(du)、靈敏度(du)較低。此外，其(qi)(qi)稱(cheng)(cheng)重(zhong)(zhong)(zhong)(zhong)結(jie)果還(huan)因重(zhong)(zhong)(zhong)(zhong)力(li)(li)加速度(du)的(de)(de)(de)不(bu)同(tong)而(er)(er)有所差異。

二、彈簧秤的使用

在使用彈(dan)(dan)簧(huang)(huang)測(ce)力計之前，必須(xu)認清(qing)其(qi)構造，主要有彈(dan)(dan)簧(huang)(huang)、指針(zhen)、鐵桿(gan)和掛鉤等等。

(1)首先(xian)要看清其量程，所要測量的力不能超過它的量程.因為彈(dan)簧是有(you)(you)一(yi)定彈(dan)性限(xian)度(du)(du)的，超過這個限(xian)度(du)(du)測量就不準確，還有(you)(you)可能損壞測力計。

(2)測(ce)量(liang)前要(yao)看清楚彈簧(huang)測(ce)力計的分度值(zhi)，以便測(ce)量(liang)時(shi)讀(du)數。

(3)測量前要(yao)檢查指(zhi)(zhi)針是否指(zhi)(zhi)在零刻度(du)(du)(du)線(xian)(xian).如果沒(mei)有指(zhi)(zhi)在零刻度(du)(du)(du)線(xian)(xian)，要(yao)進行調(diao)節使指(zhi)(zhi)針指(zhi)(zhi)在零刻度(du)(du)(du)線(xian)(xian)。

(4)使用(yong)前，要輕(qing)輕(qing)地來回拉動彈簧(huang)測力計的掛鉤(gou)，以(yi)免指針被卡住，給測量帶來較(jiao)大的誤(wu)差。

(5)測(ce)量時(shi)，拉彈簧測(ce)力計掛鉤的(de)力要和測(ce)力計的(de)外殼(ke)平行，避免扭曲和摩(mo)(mo)擦(ca)，盡量減小(xiao)由于摩(mo)(mo)擦(ca)產生的(de)測(ce)量誤差。

(6)要等到示數(shu)穩定后再讀(du)數(shu)，讀(du)數(shu)時視(shi)線要與刻度面(mian)(mian)板表面(mian)(mian)垂直(zhi)。