问题 问答题

如图所示,在正点电荷Q的一条电场线上的A处,放一个电荷量大小为4.0×10-6C的正点电荷q1,q1受到的电场力F1=1.2×10-2N.求:

(1)A点处的电场强度EA的大小和方向如何?

(2)如果在A处换上另一个电荷量大小为3.0×10-6C的负点电荷q2,它所受到的电场力F2的大小和方向如何?

(3)若再A处不放电荷,则该处的电场强度多大?

答案

(1)由电场强度的定义式可得

A点处电场强度大小:EA=

F1
q1
=
1.2×10-2
4.0×10-6
=3×105N/C

电场强度的方向:从Q指向A点.

(2)负点电荷q2受到的电场力的大小F2=q2EA=3.0×10-6×3.0×105=0.9N

其方向:指向正点电荷Q向左

(3)若在A处不放电荷,该处的电场强度不变,仍为3×105N/C,

答:(1)A点处的电场强度的大小为3×105N/C,方向为从Q指向A点.

(2)负点电荷q2受到的电场力F2的大小为0.9N,方向为指向正点电荷Q向左.

(3)若再A处不放电荷,则该处的电场强度仍为3×105N/C.

阅读理解

阅读下列材料,从所给的六个选项(A、B、C、D、E和F)中,选出符合各小题要求的最佳选项,并在答题卡上写上答案。选项中有一项为多余选项。

The people below are all looking for a hotel in Scotland for their holidays. After the description of these people, there is information about six Scotland hotels A-F. Decide which hotel would be most suitable for the people mentioned in questions 1-5 and then mark the correct letter(A-F) on your answer sheet. There is one extra paragraph about one hotel which you don’t need to use.

________小题1:Two women friends who want to do several all-day hikes in the mountains during the spring. They like a place with traditional decorations and wonderful views

______小题2:A woman with two children aged six and ten, who will spend July in Scotland. The children are interested in animals and plants and the mother enjoys fashions.

________小题3:A handicapped lawyer who must use a wheelchair but drives her own car. She enjoys concerts, museums, fine architecture and swimming. She will spend the first two weeks of October in Scotland.

__________小题4:A writer, a teacher and their one-year-old daughter. They want to be in a quiet place during August. They enjoy good food, and like to take long walks(the baby rides in a back-pack).

_________小题5:An old couple, aged 65 and 68. They love mountain scenery and still take easy walks by the lakeside when they can. They hope to enjoy fresh air and some relaxing activities.

A.Edinburgh. Post House

A popular base for visitors to Edinburgh, this fine hotel stands next to the zoological Gardens within easy reach of the many famous sights, shops and entertainments of one of Europe’s most elegant capitals.

B.Gatehouse of Fleet. Cally Hotel

This impressive hotel, well-known for its good Scottish cooking, is an ideal choice for a relaxing family holiday. Set in 100 acres of private grounds, the Cally, a former stately home, has something for everyone including its own fishing lake, outdoor heated swimming pool, green lawn, tennis court, children’s playground and sauna baths.

C.Glenborrodale. Glenborrodale Castle Hotel

There can be few better places for a refreshing holiday than this picturesque hotel set in its own 120 acres of beautiful countryside by charming Lake Sunart on the Ardnamurchan Peninsular(半岛). Boating and fishing are both available here.

D.Inverness. Royal Hotel!A unique feature(特点) of the Royal is its fine collection of antique(made in earlier times) furniture, china and glass. This friendly comfortable hotel, a favourite meeting place for the townspeople, is an excellent base for getting to know the Highlands-Lake Ness, Great Gien and Culloden Moor are all within easy reach.

E.Peebles. Tontine Hotel

The Tontine had a fascinating beginning-it was built in 1808. This homely hotel has been extended to make it a really comfortable base for exploring the Tweed Valley and the attractive Lowland country.

F.North Berwick. Marine Hotel

Fine hotel overlooks the famous West Links golf course and is close to several sandy beaches. The Marine has its own open-air swimming pool as well as tennis courts, squash courts and saunas. Edinburgh, well-known for its art festivals, is only some 24 miles away.

判断题