Question

two bulbs have the following ratings :

a. 40w,200v

b. 20w,110v

what is the ratio their resistances?

Answer 1

Heya!!

Let two resistances be R1 & R2 :

A) Since R = V^2 / P

=) R1 = 200*200/40

= 1000 ohms

B) R2 = 110*110 / 20

= 605 ohms

So R1/R2 = 1000/605

= 200/121

Hope it helps uh!!

Answer 2

$\huge{hey}$

$\huge{ \mathfrak{here \: is \: answer}}$

$\bf{given}$

power=40w

voltage=200v


power'=20w

voltage'=110v

using formula we get

R1=v1²/p1

R2=v2²/p2
$\sf{ \frac{r \tiny1}{r \tiny2} = \frac{ {v \tiny1}^{2} }{ {v \tiny2}^{2} } \times \frac{p \tiny2}{p \tiny1}}$


$\bf{ \frac{ {200}^{2} }{ {110}^{2} } \times \frac{20}{40}}$

1000/605

$\bf{ \frac{200}{121}}$

$\huge \boxed{hope \: it \: helps}$

$\huge{ \mathbb{THANKS}}$