You may have had a chemistry class where you looked at atomic spectra. A topic i

Question

You may have had a chemistry class where you looked at atomic spectra. A topic in modern physics that we will not talk about is that atoms and molecules have discrete energy levels since this is covered in chemistry, but the physics behind these energy levels involves the concept of quantization–about which we will talk briefly next week.A high-voltage discharge tube is often used to study atomic spectra. The tubes require alarge voltage across the terminals to operate–same idea as the acceleration ofelectronsthat we discussed in HIP2 and 6. To get 5000V (rms) to the tube in order to dissipate 75.0Wfrom our 120V(rms)socket, you need a step-up transformer.

a)What is the ratio of the number of turns in the secondary to the number of turns in the primary?

b)What is the rms current in each of the coils?

c)What is the effective resistance that the 120-V source is subjected to?

Explanation / Answer

here,

seccondary voltage , Vs = 5000 V

power , P = 75 W

primary voltage , Vp = 120 V

a)

Ns/Np = Vs/Vp

Ns/Np = 5000 /120

Ns/Np = 41.67

the ratio of the number of turns in the secondary to the number of turns in the primary is 41.67

b)

the rms current in primary , Ip = P/Vp

Ip = 0.625 A

the rms current in the seccondary , Is = P/Vs = 0.015 A

c)

let the effective resistance be R

Vp^2 /R = P

120^2 /R = 75

R = 192 ohm

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