20160118 One question per day
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20160118 Daily Question: 1-3 points for participation; 3-5 points if the answer is correct along with an explanation. When a test pen is used to distinguish between direct current and alternating current, it is _________ when both poles of the neon tube emit light, and it is _________ when only one pole of the neon tube emits light. Answer: Alternating current Direct current
When both poles of the neon tube emit light, it is __alternating current________; when only one pole of the neon tube emits light, it is __direct current________.
When a voltage tester is used to distinguish between direct current and alternating current, if both poles of the neon tube glow, it is alternating current; if only one pole of the neon tube glows, it is direct current.
Electricity that is bright on both ends is alternating current, while that which is bright on one end only is direct current. The direction of alternating current changes, while the direction of direct current remains constant. Moreover, the voltage of direct current must reach a certain level; if it is too low, it cannot be measured.