Question

In: Physics

The rechargeable batteries for a laptop computer need a much smaller voltage than what a wall...

The rechargeable batteries for a laptop computer need a much smaller voltage than what a wall socket provides. Therefore, a transformer is plugged into the wall socket and produces the necessary voltage for charging the batteries. The batteries are rated at 9.0 V, and a current of 272 mA is used to charge them. The wall socket provides a voltage of 120 V.

(a) Determine the turns ratio of the transformer

Ns/Np =

(b) What is the current coming from the wall socket?
I_p =

(c) Find the average power delivered by the wall socket and the average power sent to the batteries.
P_p =
P_s =

Expert Solution

Since efficiency of transformer is notgiven, i assume that the tranformer is ideal.

For an ideal transformer

inputpower = output power

V_S /V_P= N_S /N_P= I_P /I_S

a. N_S /N_P= V_S /V_P

= 9.0/ 120

= 3/ 40

= 0.075

b. I_P /I_S= V_S /V_P

Current from the wallsocket I_P = 0.075* I_S

= 0.075* 272 mA

= 20.4 mA

c. Power delivered by wallsocket P_P= V_P* I_P

= 120* 20.4 * 10^-3

= 2.448 W

Powersupplied to thebattery P_S= V_S* I_S

= 9.0* 272 * 10^-3

= 2.448 W

genius_generous answered 1 month ago

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