题干


如图所示,图1是某同学设计的电容式速度传感器原理图,其中上板为固定极板,下板为待测物体,在两极板间电压恒定的条件下,极板上所带电量Q将随待测物体的上下运动而变化,若Q随时间t的变化关系为Q=
b
t
+
a
ab为大于零的常数),其图象如题21图2所示,那么题21图3、图4中反映极板间场强大小E和物体速率vt变化的图线可能是




A:①和③

B:①和④

C:②和③

D:②和④

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答案(点此获取答案解析)

C

同类题5

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    Guided Walking Week April 2016

    Dates: April 30th-May 7th 2016

    Location: Abdet, Costa Blanca

    A week of guided walking in the mountains around Abdet. Highlights include the climbing of Valencia's highest summit (Sierra de Aitana), traveling completely around the impressive Puig Campana, and several explorations in the Sierra de Aitana. Ancient trails lead through spectacular canyons(峡谷) to abandoned settlements situated high in the mountains. You will discover the snow trader routes which lead from the incredible snow holes high in the mountains down to the villages and towns on the coast. These years, golden eagles have made a return to this area, and you may also see other animals—wild goats, foxes, wild pigs and red squirrels.

    As part of the week you are invited to help clear some local walking paths. This involves clearing collapsed (坍塌的) walls and rocks, cutting back fallen trees. This is of course optional and is just for half a day, it's actually great fun!

Price:$499

Includes:

    Accommodation in the beautiful mountain village of Abdet

    All food-good home cooking

    Beer, wine, soft drinks

    Snacks and post walk treats

    Packed lunches & drinks(except café/bar visits)

    Expert guiding

    Photos/Videos of your days in the mountains

    Airport pick-up/return $25 each way(fly to Alicante)

    Single room supplement $75

    To book or get further information, please contact info@abdet.com.