Bez elektrickej energie by nefungovali naše telefóny, počítače ani svetlá... Show more
Fyzika
Slovenský jazyk
Angličtina
MatematikaSign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
31
•
Updated Mar 25, 2026
•
Elektrické napätie a odpor - základné pojmy
1 / 7
Základné pojmy elektrickej energie
Elektrina funguje podobne ako voda v potrubí, len namiesto vody sa pohybujú elektróny. Elektrické napätie (U) je ako tlak, ktorý tlačí elektróny cez obvod - bez neho by sa elektróny nepohybovali vôbec.
Elektrický prúd (I) už poznáš - to je usporiadaný pohyb elektrónov v obvode. Predstav si ho ako množstvo vody, ktoré pretečie potrubím za určitý čas. Meria sa v ampéroch (A) pomocou ampérmetra.
Elektrický odpor (R) je vlastnosť materiálu, ktorá bráni toku prúdu. Je to ako zúženie v potrubí alebo špongia, ktorá spomaľuje tok vody. Čím väčší odpor, tým ťažšie sa elektrónom prechádza a meria sa v ohmoch (Ω).
💡 Tip na zapamätanie: Napätie "tlačí", odpor "bráni", prúd "tečie"!
Elektrické napätie - "tlak" elektriny
Napätie je práca, ktorú vykoná elektrické pole pri prenose náboja z jedného miesta na druhé. Batéria má na jednom konci viac elektrónov ako na druhom - tento rozdiel "tlačí" elektróny, aby sa pohybovali.
Napätie sa počíta podľa vzorca U = W/Q, kde W je práca v jouloch a Q je náboj v coulomboch. Jednotka napätia je volt (V) a meriame ho voltmetrom.
Voltmeter sa vždy zapája paralelne (vedľa spotrebiča), pretože meria rozdiel "tlaku" medzi dvoma bodmi. Bez napätia by elektróny netiekli vôbec - je to ako vypnutý kohútik pri vode.
⚠️ Pozor: Vysoké napätie môže byť nebezpečné! Nikdy sa nepokúšaj pracovať s elektrinou v zásuvke bez dozoru dospelého.
Elektrický odpor a čo ho ovplyvňuje
Každý materiál kladie elektrónom určitý odpor. Kovy ako med majú malý odpor (sú to vodiče), zatiaľ čo plast má veľký odpor (je to izolant).
Na odpor vodiča vplýva niekoľko vecí. Materiál - med vedie lepšie ako železo. Dĺžka - čím dlhší vodič, tým väčší odpor. Prierez - čím hrubší vodič, tým menší odpor.
Vzorec pre odpor je R = ρl/S, kde ρ (ró) je rezistivita materiálu, l je dĺžka a S je prierez vodiča. Rezistor je súčiastka s presne definovaným odporom, ktorá obmedzuje prúd v obvode.
🔧 Prakticky: Hrubé káble majú malý odpor a vedú viac prúdu - preto sa používajú vo varných konvičkách!
Ohmov zákon - najdôležitejší vzťah
Ohmov zákon spája napätie, prúd a odpor do jedného vzorca: U = R × I. Hovorí, že prúd je priamo úmerný napätiu a nepriamo úmerný odporu.
Na zapamätanie používaj trojuholník: U hore, I a R dole. Ak chceš vypočítať jednu veličinu, zakryj ju a uvidíš vzorec. Pre prúd: I = U/R, pre odpor: R = U/I.
Logika je jednoduchá - ak zvýšiš napätie, prúd sa zväčší (väčší tlak). Ak zvýšiš odpor, prúd sa zmenší (väčšia prekážka). Toto pochopenie ti pomôže pri riešení všetkých úloh.
✅ Dôležité: Vždy kontroluj jednotky! 1 mA = 0,001 A, 1 kV = 1000 V.
Riešenie príkladov krok za krokom
Pozrime si praktické príklady. Príklad 1: Žiarovka má odpor 10 Ω, batéria 4,5 V. Aký prúd? Použijem I = U/R = 4,5 V / 10 Ω = 0,45 A.
Príklad 2: Varič s prúdom 5 A a napätím 230 V. Aký odpor? R = U/I = 230 V / 5 A = 46 Ω.
Príklad 3: Rezistor 100 Ω, prúd 0,2 A. Aké napätie? U = R × I = 100 Ω × 0,2 A = 20 V.
📝 Postup: Vždy napíš zápis (čo viem, čo hľadám), vyber vzorec, dosad čísla a vypočítaj.
Meranie a bezpečnostné pravidlá
Voltmeter sa zapája paralelne (vedľa spotrebiča), ampérmeter sériovo (do série s obvodom). Toto je veľmi dôležité pre správne meranie.
Pri prepočtoch jednotiek dávaj pozor: 1 mA = 0,001 A, 1 kV = 1000 V. Vždy používaj základné jednotky (V, A, Ω) vo vzorcoch.
Bezpečnosť je na prvom mieste! Vysoké napätie a prúd môžu byť smrteľné. Nikdy neopravuj elektrické zariadenia bez znalostí a dozoru dospelého.
🎯 Na skúšku si zapamätaj: U (volt, voltmeter, paralelne), I (ampér, ampérmeter, sériovo), R (ohm, bráni prúdu), Ohmov zákon U = R × I.
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content in Fyzika
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5
App Store
4.7/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Elektrické napätie a odpor - základné pojmy
Bez elektrickej energie by nefungovali naše telefóny, počítače ani svetlá doma. Aby si pochopil/a, ako elektrina funguje, musíš najprv pochopiť tri základné pojmy: napätie, prúd a odpor. Predstav si elektrickú energiu ako vodu tečúcu v potrubí - všetko začne dávať... Show more
Základné pojmy elektrickej energie
Elektrina funguje podobne ako voda v potrubí, len namiesto vody sa pohybujú elektróny. Elektrické napätie (U) je ako tlak, ktorý tlačí elektróny cez obvod - bez neho by sa elektróny nepohybovali vôbec.
Elektrický prúd (I) už poznáš - to je usporiadaný pohyb elektrónov v obvode. Predstav si ho ako množstvo vody, ktoré pretečie potrubím za určitý čas. Meria sa v ampéroch (A) pomocou ampérmetra.
Elektrický odpor (R) je vlastnosť materiálu, ktorá bráni toku prúdu. Je to ako zúženie v potrubí alebo špongia, ktorá spomaľuje tok vody. Čím väčší odpor, tým ťažšie sa elektrónom prechádza a meria sa v ohmoch (Ω).
💡 Tip na zapamätanie: Napätie "tlačí", odpor "bráni", prúd "tečie"!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Elektrické napätie - "tlak" elektriny
Napätie je práca, ktorú vykoná elektrické pole pri prenose náboja z jedného miesta na druhé. Batéria má na jednom konci viac elektrónov ako na druhom - tento rozdiel "tlačí" elektróny, aby sa pohybovali.
Napätie sa počíta podľa vzorca U = W/Q, kde W je práca v jouloch a Q je náboj v coulomboch. Jednotka napätia je volt (V) a meriame ho voltmetrom.
Voltmeter sa vždy zapája paralelne (vedľa spotrebiča), pretože meria rozdiel "tlaku" medzi dvoma bodmi. Bez napätia by elektróny netiekli vôbec - je to ako vypnutý kohútik pri vode.
⚠️ Pozor: Vysoké napätie môže byť nebezpečné! Nikdy sa nepokúšaj pracovať s elektrinou v zásuvke bez dozoru dospelého.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Elektrický odpor a čo ho ovplyvňuje
Každý materiál kladie elektrónom určitý odpor. Kovy ako med majú malý odpor (sú to vodiče), zatiaľ čo plast má veľký odpor (je to izolant).
Na odpor vodiča vplýva niekoľko vecí. Materiál - med vedie lepšie ako železo. Dĺžka - čím dlhší vodič, tým väčší odpor. Prierez - čím hrubší vodič, tým menší odpor.
Vzorec pre odpor je R = ρl/S, kde ρ (ró) je rezistivita materiálu, l je dĺžka a S je prierez vodiča. Rezistor je súčiastka s presne definovaným odporom, ktorá obmedzuje prúd v obvode.
🔧 Prakticky: Hrubé káble majú malý odpor a vedú viac prúdu - preto sa používajú vo varných konvičkách!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Ohmov zákon - najdôležitejší vzťah
Ohmov zákon spája napätie, prúd a odpor do jedného vzorca: U = R × I. Hovorí, že prúd je priamo úmerný napätiu a nepriamo úmerný odporu.
Na zapamätanie používaj trojuholník: U hore, I a R dole. Ak chceš vypočítať jednu veličinu, zakryj ju a uvidíš vzorec. Pre prúd: I = U/R, pre odpor: R = U/I.
Logika je jednoduchá - ak zvýšiš napätie, prúd sa zväčší (väčší tlak). Ak zvýšiš odpor, prúd sa zmenší (väčšia prekážka). Toto pochopenie ti pomôže pri riešení všetkých úloh.
✅ Dôležité: Vždy kontroluj jednotky! 1 mA = 0,001 A, 1 kV = 1000 V.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Riešenie príkladov krok za krokom
Pozrime si praktické príklady. Príklad 1: Žiarovka má odpor 10 Ω, batéria 4,5 V. Aký prúd? Použijem I = U/R = 4,5 V / 10 Ω = 0,45 A.
Príklad 2: Varič s prúdom 5 A a napätím 230 V. Aký odpor? R = U/I = 230 V / 5 A = 46 Ω.
Príklad 3: Rezistor 100 Ω, prúd 0,2 A. Aké napätie? U = R × I = 100 Ω × 0,2 A = 20 V.
📝 Postup: Vždy napíš zápis (čo viem, čo hľadám), vyber vzorec, dosad čísla a vypočítaj.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Meranie a bezpečnostné pravidlá
Voltmeter sa zapája paralelne (vedľa spotrebiča), ampérmeter sériovo (do série s obvodom). Toto je veľmi dôležité pre správne meranie.
Pri prepočtoch jednotiek dávaj pozor: 1 mA = 0,001 A, 1 kV = 1000 V. Vždy používaj základné jednotky (V, A, Ω) vo vzorcoch.
Bezpečnosť je na prvom mieste! Vysoké napätie a prúd môžu byť smrteľné. Nikdy neopravuj elektrické zariadenia bez znalostí a dozoru dospelého.
🎯 Na skúšku si zapamätaj: U (volt, voltmeter, paralelne), I (ampér, ampérmeter, sériovo), R (ohm, bráni prúdu), Ohmov zákon U = R × I.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
0
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Mock Exam
Quiz
Flashcards
Essay
Most popular content in Fyzika
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5
App Store
4.7/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user