2 question

Dear student

Please ask one question in one query. I'm doing first one.

t h e t w o w i r e s a r e m a d e o f s a m e m e t a l s o t h e r r e s i s t i v i t y w i l l b e s a m e a n d h a v e e q u a l l e n g t h . T h e r e s i s \tan c e o f a w i r e o f l e n g t h i s g i v e n b y R = \frac{ρ l}{A} R \propto \frac{1}{A} \frac{R_{A}}{R_{B}} = \frac{A_{B}}{A_{A}} \frac{4 R_{B}}{R_{B}} = \frac{A_{B}}{A_{A}} s o \frac{A_{A}}{A_{B}} = \frac{1}{4}