[电] scale length of an indicating ins-trument

zhǐ shì yí qì de biāo chǐ cháng dù ㄓˇ ㄕˋ ㄧˊ ㄑㄧˋ ㄉㄜ˙ ㄅㄧㄠ ㄔˇ ㄔㄤˊ ㄉㄨˋ