The rechargeable batteries for a laptop computer need a muchsmaller voltage than

Question

The rechargeable batteries for a laptop computer need a muchsmaller voltage than what a wall socket provides. Therefore, atransformer is plugged into the wall socket and produces thenecessary voltage for charging the batteries. The batteries arerated at 9.0 V, and a current of 268 mA isused to charge them. The wall socket provides a voltage of 120V.

(a) Determine the turns ratio of the transformer.
Ns/Np=



(b) What is the current coming from the wall socket?
Ip = 23

(c) Find the average power delivered by the wall socket and theaverage power sent to the batteries.
Pp = 4
Ps = 6

Thanks for your help! :)
Ns/Np=

Ns/Np=

Explanation / Answer

   a.   NS /NP   =   VS /VP                         =   9.0/ 120 = 0.075

   b.   IP /IS   =   VS /VP                         =   9.0/ 120 = 0.075
     Current from the wallsocket   IP  =   0.075 * IS                                                          =   0.075* 268 mA                                                     = 20.1 mA
                                                         =   0.075* 268 mA                                                     = 20.1 mA

   c.   Power delivered by wallsocket   PP   =   VP* IP                                                                   =   120* 20.1 * 10-3                                                                = 2.412 W
        Power supplied to thebattery   PS   =   VS* IS                                                                =   9.0* 268 * 10-3                                                               = 2.412 W                                                               = 2.412 W

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