Consider the following statements regarding Skin Effect:
1. Skin effect causes current to concentrate near surface of conductor at high frequency.
2. Skin depth decreases with increase in frequency.
3. Skin effect reduces effective cross-sectional area of conductor.
4. Skin effect is significant only at low frequencies.
Which of the above statements is/are correct?
Answer & step-by-step solution
Skin effect is the tendency of alternating current to crowd toward a conductor surface as frequency rises. Skin depth decreases with frequency and also depends on permeability and conductivity. Key relation: δ=√(2/(ωμσ)).
Exam focus: Higher f → smaller skin depth → higher AC resistance. Common trap: Skin effect is weak at low frequency and stronger at high frequency.
Statement-wise Verification
- Statement 1 - Correct.
Skin effect causes current to concentrate near surface of conductor at high frequency.
Skin effect is the tendency of alternating current to crowd toward a conductor surface as frequency rises. - Statement 2 - Correct.
Skin depth decreases with increase in frequency.
Skin depth decreases with frequency and also depends on permeability and conductivity. - Statement 3 - Correct.
Skin effect reduces effective cross-sectional area of conductor.
Skin effect is the tendency of alternating current to crowd toward a conductor surface as frequency rises. - Statement 4 - Incorrect.
Skin effect is significant only at low frequencies.
Skin effect becomes more pronounced as frequency increases
Core Concept
Skin effect is the tendency of alternating current to crowd toward a conductor surface as frequency rises. The effective conducting area falls, causing AC resistance to increase. Skin depth decreases with frequency and also depends on permeability and conductivity.
Formula / Key Relationship
δ=√(2/(ωμσ)).
Why the Other Options Are Wrong
Option A is incorrect because it omits correct statement(s) 2. Option B is incorrect because it includes incorrect statement(s) 4 and omits correct statement(s) 2, 3. Option C is incorrect because it omits correct statement(s) 1.
Exam Shortcut / Approach
Higher f → smaller skin depth → higher AC resistance.
Common Mistake
Skin effect is weak at low frequency and stronger at high frequency.
Quick Revision
Skin Depth and AC Resistance is linked with Skin Effect, Transmission Lines and Power Systems. Higher f → smaller skin depth → higher AC resistance.
स्किन इफेक्ट के संबंध में निम्नलिखित कथनों पर विचार कीजिए:
1. उच्च आवृत्ति पर स्किन इफेक्ट धारा को चालक की सतह के पास केंद्रित करता है।
2. आवृत्ति बढ़ने पर स्किन डेप्थ घटती है।
3. स्किन इफेक्ट चालक का प्रभावी अनुप्रस्थ-काट क्षेत्रफल घटाता है।
4. स्किन इफेक्ट केवल निम्न आवृत्तियों पर महत्वपूर्ण है।
उपरोक्त में से कौन-सा/से कथन सही है/हैं?
उत्तर और चरणबद्ध हल
D — केवल 1, 2 और 3। δ = √(2/(ωμσ)), इसलिए आवृत्ति बढ़ने पर स्किन डेप्थ घटती है, धारा सतह पर सिमटती है और प्रभावी क्षेत्रफल घटने से AC प्रतिरोध बढ़ता है। निम्न आवृत्ति पर स्किन इफेक्ट कमज़ोर होता है।
विस्तृत हल (मूल भाषा में)
Statement-wise Verification
- Statement 1 - Correct.
Skin effect causes current to concentrate near surface of conductor at high frequency.
Skin effect is the tendency of alternating current to crowd toward a conductor surface as frequency rises. - Statement 2 - Correct.
Skin depth decreases with increase in frequency.
Skin depth decreases with frequency and also depends on permeability and conductivity. - Statement 3 - Correct.
Skin effect reduces effective cross-sectional area of conductor.
Skin effect is the tendency of alternating current to crowd toward a conductor surface as frequency rises. - Statement 4 - Incorrect.
Skin effect is significant only at low frequencies.
Skin effect becomes more pronounced as frequency increases
Core Concept
Skin effect is the tendency of alternating current to crowd toward a conductor surface as frequency rises. The effective conducting area falls, causing AC resistance to increase. Skin depth decreases with frequency and also depends on permeability and conductivity.
Formula / Key Relationship
δ=√(2/(ωμσ)).
Why the Other Options Are Wrong
Option A is incorrect because it omits correct statement(s) 2. Option B is incorrect because it includes incorrect statement(s) 4 and omits correct statement(s) 2, 3. Option C is incorrect because it omits correct statement(s) 1.
Exam Shortcut / Approach
Higher f → smaller skin depth → higher AC resistance.
Common Mistake
Skin effect is weak at low frequency and stronger at high frequency.
Quick Revision
Skin Depth and AC Resistance is linked with Skin Effect, Transmission Lines and Power Systems. Higher f → smaller skin depth → higher AC resistance.
સ્કિન ઇફેક્ટ અંગે નીચેનાં વિધાનો ધ્યાનમાં લો:
1. ઊંચી આવૃત્તિએ સ્કિન ઇફેક્ટ પ્રવાહને વાહકની સપાટી નજીક કેન્દ્રિત કરે છે.
2. આવૃત્તિ વધતાં સ્કિન ડેપ્થ ઘટે છે.
3. સ્કિન ઇફેક્ટ વાહકનું અસરકારક આડછેદ ક્ષેત્રફળ ઘટાડે છે.
4. સ્કિન ઇફેક્ટ ફક્ત નીચી આવૃત્તિએ જ મહત્વની છે.
ઉપરોક્તમાંથી કયું/કયાં વિધાન સાચું/સાચાં છે?
જવાબ અને પગલાવાર ઉકેલ
D — ફક્ત 1, 2 અને 3. δ = √(2/(ωμσ)), તેથી આવૃત્તિ વધતાં સ્કિન ડેપ્થ ઘટે છે, પ્રવાહ સપાટી પર સંકેન્દ્રિત થાય છે અને અસરકારક ક્ષેત્રફળ ઘટતાં AC અવરોધ વધે છે. નીચી આવૃત્તિએ સ્કિન ઇફેક્ટ નબળી હોય છે.
વિગતવાર ઉકેલ (મૂળ ભાષામાં)
Statement-wise Verification
- Statement 1 - Correct.
Skin effect causes current to concentrate near surface of conductor at high frequency.
Skin effect is the tendency of alternating current to crowd toward a conductor surface as frequency rises. - Statement 2 - Correct.
Skin depth decreases with increase in frequency.
Skin depth decreases with frequency and also depends on permeability and conductivity. - Statement 3 - Correct.
Skin effect reduces effective cross-sectional area of conductor.
Skin effect is the tendency of alternating current to crowd toward a conductor surface as frequency rises. - Statement 4 - Incorrect.
Skin effect is significant only at low frequencies.
Skin effect becomes more pronounced as frequency increases
Core Concept
Skin effect is the tendency of alternating current to crowd toward a conductor surface as frequency rises. The effective conducting area falls, causing AC resistance to increase. Skin depth decreases with frequency and also depends on permeability and conductivity.
Formula / Key Relationship
δ=√(2/(ωμσ)).
Why the Other Options Are Wrong
Option A is incorrect because it omits correct statement(s) 2. Option B is incorrect because it includes incorrect statement(s) 4 and omits correct statement(s) 2, 3. Option C is incorrect because it omits correct statement(s) 1.
Exam Shortcut / Approach
Higher f → smaller skin depth → higher AC resistance.
Common Mistake
Skin effect is weak at low frequency and stronger at high frequency.
Quick Revision
Skin Depth and AC Resistance is linked with Skin Effect, Transmission Lines and Power Systems. Higher f → smaller skin depth → higher AC resistance.
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