Câu 1: 

Điện trở là:

\(R = \rho \dfrac{l}{S} = 1,{7.10^{ - 8}}.\dfrac{{10000.1000}}{{0,{{5.10}^{ - 6}}}} = 340000\Omega \)

Công suất hao phí:

\({P_{hp}} = {\left( {\dfrac{P}{U}} \right)^2}R = {\left( {\dfrac{{{{10.10}^6}}}{{{{500.10}^3}}}} \right)^2}.340000 = 136000000W\)

Câu 2:

Hình vẽ 1 + 2

Câu 3:

Hình 1

Ta có:

\(\begin{array}{l}
\dfrac{{AB}}{{A'B'}} = \dfrac{{OA}}{{OA'}} = \dfrac{8}{{OA'}}\\
\dfrac{{AB}}{{A'B'}} = \dfrac{{OI}}{{A'B'}} = \dfrac{{OF'}}{{OA' + OF'}} = \dfrac{{12}}{{OA' + 12}}\\
 \Rightarrow \dfrac{8}{{OA'}} = \dfrac{{12}}{{OA' + 12}} \Rightarrow OA' = 24cm\\
 \Rightarrow \dfrac{{AB}}{{A'B'}} = \dfrac{1}{3} \Rightarrow A'B' = 3cm
\end{array}\)

Câu 4:

Hình 3

\(\begin{array}{l}
\dfrac{{AB}}{{A'B'}} = \dfrac{{OA}}{{OA'}} = \dfrac{{15}}{{OA'}}\\
\dfrac{{AB}}{{A'B'}} = \dfrac{{OI}}{{A'B'}} = \dfrac{{OF'}}{{OA' - OF'}} = \dfrac{{10}}{{OA' - 10}}\\
 \Rightarrow \dfrac{{15}}{{OA'}} = \dfrac{{10}}{{OA' - 10}} \Rightarrow OA' = 30cm
\end{array}\)