Известно, что электромагнитные волны распространяются в веществе с конечной скоростью, определяемой выражением v=1/√(εε_0 μμ_0 ), где ε и μ - диэлектрическая и магнитная проницаемость вещества соответственно, ε0=8,85⋅10−12 Ф/м, μ0=4π⋅10−7 Гн/м. Определи длину электромагнитной волны λ с частотой ν=750 ТГц в немагнитной среде, если её скорость в данной среде составляет v=2,15⋅108 м/с. Чему равна диэлектрическая проницаемость вещества для волн указанной частоты? Длину волны вырази в нм, округлив результат до двух значащих цифр, а диэлектрическую проницаемость округли до десятых долей. (11 А Шацк)

Объяснение:

№1

P = IU = I²R

P1/P2 = ( ( 2I )²( R/4 ) )/( I²R ) = ( I²R )/( I²R ) = 1

№2

η = Рпол./Рзат. * 100%

η = ( I2U2 )/( I1U1 ) 100%

I1 = ( I2U2 )/( ηU1 ) 100%

I1 = ( 9 * 22 )/( 90% * 220 ) 100% = 1 A

№3

λ = Тv

λ = 2π√( LCоб. )v

λ = 2π√( L( C1 + C2 ) )v

λ = 2 * 3,14 √( 10 * 10^-3 ( 360 * 10^-12 + 40 * 10^-12 ) ) 3 * 10^8 = 2 * 3,14 √( 10^-2 ( ( 36 + 4 ) 10^-11 ) 3 * 10^8 = 3768 м

№4

WC( max ) = ( CU( max )² )/2

WL( max ) = ( LI( max )² )/2

W = WC( max ) = WL( max )

( CU( max )² )/2 = ( LI( max )² )/2

CU( max )² = LI( max )²

С = ( LI( max )² )/( U( max )² )

W = WC + WL

W = ( CU² )/2 + ( LI² )/2

( CU( max )² )/2 = ( CU² )/2 + ( LI² )/2

CU( max )² = CU² + LI²

LI( max )² = ( LI( max )²U² )/U( max )² + LI²

LI( max )² = L ( I( max )²U² )/U( max )² + I² )

I( max )² = ( I( max )²U² )/U( max )² + I²

Подставим численные данные и решим уравнение

( 5 * 10^-3 )² = ( ( 5 * 10^-3 )²U²/2² ) + ( 3 * 10^-3 )²

2,5 * 10^-5 = 6,25 * 10^-6U² + 9 * 10^-6

( 25 - 9 ) 10^-6 = 6,25 * 10^-6U²

16 = 6,25U²

U = √( 16/6,25 ) = 1,6 B

Rome is not only an ancient city or a capital of Italy. It is a special place where everyone can feel himself at home. You will never be alone in Rome, because it seems that all people know each other and even tourists don’t feel uncomfortable there.

Rome is obviously an amazing city where you can see and visit such famous monuments as the Colosseum, the Roman Forum, the Pantheon, the Trevi Fountain and Vatican City. All these and many other tourist attractions amaze and make such a great impression that you will never be able to forget them.

Apart from sightseeing, you can also explore Italian culture in Rome. You can feel yourself a part of a mysterious rite entering any patisserie or bar in the morning. Once you share your breakfast consisting of a cup of creamy cappuccino and filled croissant with those Italians who come to that place, you will become more relaxed and even “Italian”.

And finally, you can enjoy yourself in a big park area in Rome. It is called “Villa Borghese” and it is a perfect place to spend a hot and sunny day under its trees or to walk its wide paths in. In addition, Villa Borghese can offer you different other activities. You can visit famous “Borghese Gallery” and also a zoo placed in the park.

Consequently, Rome is a city where everyone can find his place. You can walk, visit museums, do shopping, go to opera and do many other things there. But there’s one thing that you will certainly do in Rome – you will enjoy yourself.

Объяснение: