CAIE ALevel物理（9702）易错题分析

CAIE ALevel物理（9702）易错题分析

考点：uncertainty和percentage uncertainty

• uncertainty=half range

• percentage uncertainty=(uncertainty÷mean) x 100%

试题来源：9702_w18_qp_11

A digital meter has an accuracy of±1%.

The meter is used to measure the current in an electrical circuit.

The reading on the meter varies between 3.04 A and 3.08A.

What is the value of the current, with its uncertainty?

A(3.06±0.02)A

B(3.06±0.04)A

C(3.06±0.05)A

D(3.06±0.07)A

错误解法：

做错的同学没有考虑到3.04和3.08这两个测量数据本身也是存在误差(±1%)的。

直接运用uncertainty公式：

uncertainty=half range=（3.08-3.04）/2