1.) An increasing number of products, such as passports and credit cards, contai
ID: 1439249 • Letter: 1
Question
1.)
An increasing number of products, such as passports and credit cards, contain an embedded radio-frequency identification chip that both stores and transmits information. The chips do not have their own power sources. Instead, they receive their power through induction from the device used to read the stored information. The reading device generates a magnetic field, and the passport or credit card containing a coil is passed through this field.
If a certain chip needs a peak induced emf of 5.0 V to operate and the magnetic field varies with time as B(t)=Bpeaksin(t), where Bpeak = 6.0 mT is the maximum magnetic field and = 8.52 × 107 s1, what value must the product AN have in order for the chip to operate, where A is the coil's surface area and N is number of turns in the coil?
AN=
2.)
The square conducting loop in (Figure 1) lies in the xyplane of an xyz coordinate system. Suppose thata = 0.20 m . The loop is in a uniform magnetic field that points in the positive z direction and is decreasing at a rate of 0.040 T/s .
What is the magnitude of the induced emf in the loop?
Express your answer with the appropriate units.
What is the direction of the induced current in the loop?
Clockswise or Counterclockwise
Explanation / Answer
2.) E = N * change in magnetic flux
E = NA*0.04
E = 0.2*0.2*0.04 = 1.6*10^-3 V
as magnetic flux is decresising so induce Emf will resist it hence direction of current will be Counter clockwise.
1.)E = N * change in magnetic flux
E = AN*Bpeaksin(t)
5 = AN *6*10^-3 sin(t)
AN = 962 m^2
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