Question

05. In the circuit below switch 1 is closed while switch 2 remains open. (a) What is the total current provided by the battery? switch! switch 2 E2R 3R R R (b) What is the current across the 2R resistor? -) What is the power used by the 2R resistor?

Answer 1

As switch 2 remains open

So current will not passes through 3R and R as, circuit is not completed so remaining circuit is

Now finding equivalent resistance.

As R and 2R is in series

So R₁ = R +2R = 3R

Now R₁ and R is in parallel so

R_equ = (3R ×R) /(3R +R)

R_equ  = 3R/4

Now total current i_t = E/R = 4E/3R

Now current across R and 2R in series is equal

R₁ = 3R

Now formula for current in R₁ parallel with R

I₁ = i_t ×R/(R₁ + R)

= 4ER/(3R(3R+R))

= 4E/12R

now power = i₁²R

=(4E/12R) ²R

= E²/9R