Question

Q4 Calculate the electric current in the given circuit when

(i) Key K1 is open and K2 is closed

(ii) both the keys are closed

(iii) K1 is closed and K2 is open​

Answer 1

Answer:

Given,

Voltage = 12V

Resistors = R1,R2,R3,R4 = 4ohm

We know that R1,R2 and R3,R4 are in series

Req = R1+R2 = 4+4 = 8ohm

Req = R3+R4 = 4+4 = 8ohm

Now there are Only two resistors R1 and R2 they are in parallel

So, Req = 1/R1+1/R2

= 1/8+1/8

= 4ohm

By applying V = IR

I = V/R

= 12 / 4

= 3Amp.

Current in the given circuit is 3Amp.

(i) Key K1 is open and K2 is closed

We know that current flows only when Key is closed. K1 is opened so the current

doesn't flows.

(ii) Both the Keys are closed

If both the keys are closed current is 3Amp.

(iii) K1 is closed and K2 is open

If K1 is closed,

The current flows through resistors R1 and R2

We know that R1 and R2 are in series

Req = 4+4 = 8ohm

Current, I = V/R

= 12/8 = 1.5Amp.