Предмет: Физика, автор: aniwashko

Ёлочная гирлянда собрана из лампочек, рассчитанных на напряжение 12В. Какое минимальное количество лампочек необходимо, чтобы включить её в сеть напряжением 220В? Дайте ответ и объясните его

Ответы

Автор ответа: larisaorlova65

3

при последовательном соединении лампочек напряжение U=U1+U2+U3+...
Лампочки все одинаковы, пусть их n штук, тогда U =n*U1 --->U1=U/n,
U1=220/12 =18,33 Но так как количество лампочек не может быть дробным, то их было 18 штук.

larisaorlova65: :))

Предыдущий вопрос

Следующий вопрос

Похожие вопросы

Предмет: Українська мова, автор: marmurinajulia

нужно визначити рід и відминок у именников у словах в школі, у дворі,в будинку,в підьизди,в одному класі, Сашку,Ігорові,на компьютері,на велосіпеді

2 года назад

Предмет: Українська мова, автор: Skryers

Допоможіть. Потрібно скласти твір на тему "Найважче творити самого себе"

2 года назад

Предмет: Английский язык, автор: zolotoy1979

Fill in particles with the phrasal verb to put.

1. It took us long to put--------- a tent.

2. Let’s put------- the date of our meeting.

3. “Put your textbooks---- and listen to me,” the teacher said.

4. I phoned you yesterday but couldn’t put----------- .

5. We can’t put------------ ------------ his carelessness.

6. They’ve put--------- the prices on oil.

7. We are going to pu----------t some pictures on the wall.

8. They decided to put---------- their guests because of the illness of their child

2 года назад

Предмет: Английский язык, автор: FUTIT

1. Ann ____ for a job since December.
a) was looking b) is looking c) has been looking d) had looked
2. You ____ many questions.
a) won’t be asked b) didn’t be asked c) hasn’t been asked d) won’t asked
3. We were late, so by the time we got there, the meeting ____.
a) started b) has started c) didn’t start d) had started
4. I saw ____ the money.
a) him to take b) him take c) he took d) he has taken
5. I don’t know ____ .
a) what is his address b) where does he live c) where is his address d) where he lives
6. Jane ____ three letters so far.
a) write b) have written c) wrote d) has written
7. ____ rich pay higher taxes?
a) Does b) Do c) Does the d) Do the
8. When ____ ?
a) they arrived b) they have arrived c) have they arrived d) did they arrive
9. He felt that he _____.
a) is following b) was followed c) was being followed d) is followed
10. What is the matter? - I ____ for David. Have you seen him anywhere?
a) look b) am looking c) have been looking d) have looked
11. I’m going to the concert tonight. The concert ____ at 7.30.
a) is starting b) start c) starts d) will start
12. Either his children or his wife ____ arriving today.
a) have b) has c) is d) are
13. As soon as I ____ reading the article, I will give it to you.
a) will finish b) shall finish c) would finish d) finish
14. My grandma makes me ____ carrots, but I prefer ice-cream.
a) eat b) eating c) to eat d) to eating
15. He promised he ____ phone me at work.
a) will b) shall c) would d) should
16. If Jane ____ with us, we would have had a good time.
a) would come b) had come c) would have come d) came
17. I don’t want to go the party. I haven’t got ____ to go with.
a) everybody b) nobody c) somebody d) anybody
18. I’m going to a party tonight. What ____ ?
a) will I wear b) shall I wear c) do I wear d) am I wearing
19. The player ____ off the field.
a) has just been sent b) was just been sent c) has just sent d) is just sent
20. They ____ cereal and fruit every morning.
a) are used to eating b) are used to eat c) used to eating d) use to eat
21. I ____ speak French quite well now.
a) may b) can c) could d) might
22. You went to London last week, ____ you?
a) didn’t b) haven’t c) aren’t d) went
23. What did he say? - I don’t know. I ____.
a) wasn’t listen b)wasn’t listening c) didn’t listen d) didn’t listening
24. When I saw the girl I was sure I ____ her before.
a) meet b) have met c) met d) had met
25. I asked two people the way to the station, but ____ of them knew.
a) none b) either c) both d)neither
26. I took my umbrella, but it didn’t rain, so I ____ it.
a)needn’t take b) didn’t have to take c) didn’t need to take d) needn’t have taken
27. He hasn’t got a car, and ____ .
a)nor she has b) neither has she c) neither she has d) she also
28. The letters haven’t been posted yet. They ____ now.
a) are typing b) are typed c) are being typed d) have been typing
29. Can you play ____ guitar?
a) - b) the c) a d) any
30. They managed to reach the village ____.
a) on own b) on their own c) of own d) of their own
31. Can you look ____ my son for an hour while I go to the dentist?
a) out b) to c) for d) after
32. I was ready to go alone, but they insisted ____ going with me.
a) on b) for c) at d) by
33. Look! Somebody has broken this vase. - Well, it wasn’t me. I ____ it.
a)didn’t do b) didn’t c)haven’t done d) wasn’t doing
34. Halloween is a public holiday ____ on October 31.
a) celebrating b)is celebrated c) celebrated d) celebrates
35. I suggest that the film ____ developed at once.
a) should be b) would have been c) to be d) is
36. I ____ here since 1982, ever since I left school in fact.
a) live b) am living c) have lived d) lived
He managed to get out without _____ .
a) saw b) seeing c) being seen d) being looked
38. Where are the ____ people?
a) others b) other c) another d) all others
39. I feel awful. I wish I ____ so much cake.
a) haven’t eaten b) hadn’t eaten c) don’t eat d) didn’t eat
40. ____ tourists stay here.
a) Only few b) Only a few c) Only a little d) Only little
41. That box is ____ the other one.
a)more bigger than b) as big as c) as same as d) the same than
42. Your shoes are terribly dirty; they really need ____.
a) clean b) to clean c) cleaning d) cleaned
43. I heard ____ the door.
a) she lock b) her lock c) her to lock d) she locking
44. Until you ____ your homework, you won’t be allowed to go for a walk.
a) will finish b) haven’t finished c) have finished d) finished
45. You had to wait for a bus, ____ you?
a) didn’t b) hadn’t c) aren’t d) had

8 лет назад

Предмет: Математика, автор: Artem11182006

В трьох мишках яблук .В першому мишку яблок втрычи менше ниж в иншых двох , а в другому вдвичи менше чим в иншых двох, а в третьму мишку лежыть 25 яблок . Скилькы кг ядлук в трьох мишках.

8 лет назад