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Updated Mar 22, 2026
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Základy Elektrického Prúdu a Ohmovho Zákona
1 / 8
Elektrický prúd a Ohmov zákon - Základy
Elektrický prúd je ako prúd vody v rieke, len namiesto vody sa pohybujú elektróny vo vodičoch. Merá sa v Ampéroch (A) pomocou ampérmetra.
Elektrické napätie funguje ako tlak vody v potrubí - tlačí elektróny, aby sa pohybovali. Jednotka je Volt (V) a merá sa voltmetrom.
Elektrický odpor je ako zúžené potrubie, ktoré bráni toku. Čím väčší odpor, tým ťažšie sa elektróny pohybujú. Jednotka je Ohm (Ω).
💡 Tip: Predstav si elektrický obvod ako vodovodný systém - napätie je tlak, prúd je prietok a odpor sú prekážky v potrubí!
Elektrický prúd podrobnejšie
Prúd vzniká, keď sa vo vodiči začnú elektróny pohybovať usporiadane. Konvenčný smer prúdu ide od + k - pólu, ale skutočné elektróny sa pohybujú opačne.
Výpočet prúdu: I = Q/t, kde Q je náboj v coulomboch a t je čas v sekundách. Toto ti pomôže pochopiť, koľko elektrónov prejde vodičom za určitý čas.
Ampérmeter sa vždy zapája do série (za sebou) s meranou časťou obvodu - musí ním pretekať rovnaký prúd ako meranou súčiastkou.
⚠️ Pozor: Nikdy nezabudni na správne zapojenie ampérmetra - inak ho môžeš poškodiť!
Elektrické napätie a odpor
Napätie je energia, ktorá "tlačí" elektróny po obvode. Vzorec: U = W/Q, kde W je energia a Q je náboj. Voltmeter sa zapája paralelne k meranej súčiastke.
Odpor závisí od štyroch faktorov: dĺžky vodiča , plochy prierezu , materiálu a teploty.
Vzorec pre odpor: R = ρ × l/S, kde ρ (ró) je rezistivita materiálu, l je dĺžka a S je plocha prierezu.
🔍 Zaujímavosť: Meď má nízku rezistivitu (dobrý vodič), zatiaľ čo guma má vysokú (izolant).
Ohmov zákon - Kľúčový vzťah
Ohmov zákon je základný vzťah elektrotechniky: U = R × I. Napätie je priamo úmerné prúdu a odporu.
Z tohto vzorca môžeš odvodiť: I = U/R (výpočet prúdu) a R = U/I (výpočet odporu). Tento zákon platí pre väčšinu bežných súčiastok.
Pri riešení úloh si vždy najprv zapíš dané hodnoty, zvoľ správny vzorec a skontroluj jednotky. Všetko musí byť v základných jednotkách (V, A, Ω).
📝 Pamätaj: Ohmov zákon je tvoj najlepší kamarát pri riešení úloh z elektrotechniky!
Praktické príklady
Príklad 1: Žiarovka má odpor 240 Ω pri napätí 230 V. Prúd: I = U/R = 230/240 ≈ 0,96 A.
Príklad 2: Varič s prúdom 8 A pri 230 V má odpor: R = U/I = 230/8 = 28,75 Ω.
Príklad 3: LED s odporom 150 Ω a prúdom 20 mA potrebuje napätie: U = R × I = 150 × 0,02 = 3 V.
⚡ Kľúč k úspechu: Vždy preveď jednotky (mA na A, kV na V) a skontroluj si výsledok!
Praktické tipy a bezpečnosť
Jednotky sú kľúčové! Vždy skontroluj, či máš všetky veličiny v základných jednotkách. Ampérmeter zapájaj do série, voltmeter paralelne.
Ohmov zákon platí len pre ohmické odpory. Niektoré súčiastky ako diódy majú premenlivý odpor.
S elektrinou buď vždy opatrný! Vysoké napätie a prúd môžu byť nebezpečné - nikdy nepracuj bez dozoru dospelého.
🛡️ Bezpečnosť: Pri práci s elektrinou platí - radšej sa spýtaj dvakrát než riskovať úraz!
Rýchly súhrn na záver
Základné vzorce: I = Q/t (prúd), U = W/Q (napätie), R = ρl/S (odpor), U = R × I (Ohmov zákon).
Jednotky: Ampér (A) pre prúd, Volt (V) pre napätie, Ohm (Ω) pre odpor. Zapojenie: Ampérmeter do série, voltmeter paralelne.
Toto sú základy, ktoré potrebuješ vedieť na testy. S týmito vzorcami a správnym pochopením zvládneš každú úlohu z elektrotechniky!
🎯 Záver: Elektrotechnika nie je zložitá - stačí pochopiť základy a pravidelne cvičiť!
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Where can I download the Knowunity app?
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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.
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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.
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Best app on earth! no words because it’s too good
Thomas R
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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
Základy Elektrického Prúdu a Ohmovho Zákona
Elektrina je všade okolo nás - v telefónoch, počítačoch, svetlách. Ak pochopíš základy elektrického prúdu a Ohmov zákon, budeš vedieť, ako fungujú mnohé veci v tvojom živote a prečo sú niektoré obvody bezpečné a iné nie.
Elektrický prúd a Ohmov zákon - Základy
Elektrický prúd je ako prúd vody v rieke, len namiesto vody sa pohybujú elektróny vo vodičoch. Merá sa v Ampéroch (A) pomocou ampérmetra.
Elektrické napätie funguje ako tlak vody v potrubí - tlačí elektróny, aby sa pohybovali. Jednotka je Volt (V) a merá sa voltmetrom.
Elektrický odpor je ako zúžené potrubie, ktoré bráni toku. Čím väčší odpor, tým ťažšie sa elektróny pohybujú. Jednotka je Ohm (Ω).
💡 Tip: Predstav si elektrický obvod ako vodovodný systém - napätie je tlak, prúd je prietok a odpor sú prekážky v potrubí!
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Elektrický prúd podrobnejšie
Prúd vzniká, keď sa vo vodiči začnú elektróny pohybovať usporiadane. Konvenčný smer prúdu ide od + k - pólu, ale skutočné elektróny sa pohybujú opačne.
Výpočet prúdu: I = Q/t, kde Q je náboj v coulomboch a t je čas v sekundách. Toto ti pomôže pochopiť, koľko elektrónov prejde vodičom za určitý čas.
Ampérmeter sa vždy zapája do série (za sebou) s meranou časťou obvodu - musí ním pretekať rovnaký prúd ako meranou súčiastkou.
⚠️ Pozor: Nikdy nezabudni na správne zapojenie ampérmetra - inak ho môžeš poškodiť!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
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Elektrické napätie a odpor
Napätie je energia, ktorá "tlačí" elektróny po obvode. Vzorec: U = W/Q, kde W je energia a Q je náboj. Voltmeter sa zapája paralelne k meranej súčiastke.
Odpor závisí od štyroch faktorov: dĺžky vodiča , plochy prierezu , materiálu a teploty.
Vzorec pre odpor: R = ρ × l/S, kde ρ (ró) je rezistivita materiálu, l je dĺžka a S je plocha prierezu.
🔍 Zaujímavosť: Meď má nízku rezistivitu (dobrý vodič), zatiaľ čo guma má vysokú (izolant).
Sign up to see the contentIt's free!
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Ohmov zákon - Kľúčový vzťah
Ohmov zákon je základný vzťah elektrotechniky: U = R × I. Napätie je priamo úmerné prúdu a odporu.
Z tohto vzorca môžeš odvodiť: I = U/R (výpočet prúdu) a R = U/I (výpočet odporu). Tento zákon platí pre väčšinu bežných súčiastok.
Pri riešení úloh si vždy najprv zapíš dané hodnoty, zvoľ správny vzorec a skontroluj jednotky. Všetko musí byť v základných jednotkách (V, A, Ω).
📝 Pamätaj: Ohmov zákon je tvoj najlepší kamarát pri riešení úloh z elektrotechniky!
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Praktické príklady
Príklad 1: Žiarovka má odpor 240 Ω pri napätí 230 V. Prúd: I = U/R = 230/240 ≈ 0,96 A.
Príklad 2: Varič s prúdom 8 A pri 230 V má odpor: R = U/I = 230/8 = 28,75 Ω.
Príklad 3: LED s odporom 150 Ω a prúdom 20 mA potrebuje napätie: U = R × I = 150 × 0,02 = 3 V.
⚡ Kľúč k úspechu: Vždy preveď jednotky (mA na A, kV na V) a skontroluj si výsledok!
Sign up to see the contentIt's free!
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Improve your grades
Join milions of students
Praktické tipy a bezpečnosť
Jednotky sú kľúčové! Vždy skontroluj, či máš všetky veličiny v základných jednotkách. Ampérmeter zapájaj do série, voltmeter paralelne.
Ohmov zákon platí len pre ohmické odpory. Niektoré súčiastky ako diódy majú premenlivý odpor.
S elektrinou buď vždy opatrný! Vysoké napätie a prúd môžu byť nebezpečné - nikdy nepracuj bez dozoru dospelého.
🛡️ Bezpečnosť: Pri práci s elektrinou platí - radšej sa spýtaj dvakrát než riskovať úraz!
Sign up to see the contentIt's free!
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Rýchly súhrn na záver
Základné vzorce: I = Q/t (prúd), U = W/Q (napätie), R = ρl/S (odpor), U = R × I (Ohmov zákon).
Jednotky: Ampér (A) pre prúd, Volt (V) pre napätie, Ohm (Ω) pre odpor. Zapojenie: Ampérmeter do série, voltmeter paralelne.
Toto sú základy, ktoré potrebuješ vedieť na testy. S týmito vzorcami a správnym pochopením zvládneš každú úlohu z elektrotechniky!
🎯 Záver: Elektrotechnika nie je zložitá - stačí pochopiť základy a pravidelne cvičiť!
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.
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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