Pembahasan Soal Alat Ukur dan Daya Listrik sederhana

Summary

The transcript discusses various electrical concepts through calculations and diagrams. It explains how to measure current using a scale and calculates resistance using Ohm's law with a voltmeter and ammeter. The script also covers calculating power and energy consumption of a 60W light bulb at different voltages and durations, and determines the required length of a heating wire based on its resistance and voltage. It's a comprehensive tutorial on basic electrical principles and calculations.

Takeaways

• 🔍 The script discusses the calculation of electric current using a scale, where the measured current is 1/3 ampere based on the given scale.
• 🔌 It explains the use of a voltmeter and an ammeter to measure resistance (Rx), with the voltmeter having a resistance of 1 kilo Ohm and the ammeter having a resistance of 1 Ohm.
• ⚡ The calculation of Rx involves using Ohm's law (V = IR), where V is the voltage across the resistor, I is the current through the resistor, and R is the resistance.
• 💡 The script covers the concept of power in electrical circuits, including the calculation of power (P) and energy (E) for a light bulb with a rated power of 60 watts and a voltage of 220 volts.
• 🕒 The energy consumption of the light bulb is calculated over a period of 30 minutes, taking into account the power rating and the time it is used.
• 🔥 The script also discusses the power rating of a heating device and how it relates to the resistance and voltage of the wire used.
• ⏱ The calculation of the required length of wire for the heating device is based on the resistance per meter of the wire and the desired power output.
• 📏 The resistance of the wire is considered constant, and the voltage used is 125 volts, which is used to determine the necessary wire length.
• 📐 The script provides a step-by-step approach to solving electrical problems, including the use of Ohm's law and Kirchhoff's current law.
• 📋 The final calculations involve simplifying and solving equations to find the unknown variables such as the resistance (Rx) and the length of the wire needed for the heating device.

Q & A

What is the measured current if the scale reads 30 on a maximum scale of 90 with a maximum current of 1 ampere?

The measured current is 1/3 ampere, calculated by dividing the scale reading (30) by the maximum scale (90) and then multiplying by the maximum current (1 ampere).

What is the resistance (Rx) measured by the voltmeter and ammeter when the voltmeter reads 5 volts and the ammeter reads 25 milliamperes?

The resistance (Rx) is calculated using Ohm's law, V = I * Rx, where V is 5 volts and I is the total current which is 25 milliamperes (0.025 amperes). The calculated resistance is 5 volts / 0.025 amperes, which equals 200 ohms.

How do you calculate the total current flowing through the circuit when the ammeter reads 25 milliamperes and there's a known current分流 through another path?

To find the total current, you use Kirchhoff's current law which states that the total current entering a junction is equal to the total current leaving the junction. If the分流 current is known, you add it to the ammeter reading (25 milliamperes) to get the total current.

What is the power consumption of a 60-watt light bulb when connected to a 220-volt supply for 30 minutes?

The power consumption is calculated by multiplying the power rating of the bulb (60 watts) by the time it is on (30 minutes converted to hours, which is 0.5 hours). So, the energy consumed is 60 watts * 0.5 hours = 30 watt-hours.

How do you determine the resistance of a filament in a light bulb if it's rated for 60 watts at 220 volts?

Using the formula P = V^2 / R, where P is power, V is voltage, and R is resistance. Rearranging to solve for R gives R = V^2 / P. Substituting the given values (V = 220 volts, P = 60 watts) gives R = 220^2 / 60, which equals approximately 807.67 ohms.

What is the required length of wire for a 200-watt heating element with a resistance of 25 ohms per meter when used at a voltage of 125 volts?

Using the formula R = (V^2 / P) * L, where R is the resistance per meter, V is the voltage, and P is the power. Rearranging to solve for L gives L = (P / (V^2 / R)). Substituting the given values (P = 200 watts, V = 125 volts, R = 25 ohms) gives L = (200 / (125^2 / 25)), which equals approximately 1.6 meters.

How do you calculate the resistance of a wire if the power rating and voltage are known?

The resistance can be found using the formula R = V^2 / P, where V is the voltage and P is the power rating. This formula is derived from the power formula P = V * I, where I is the current, and Ohm's law V = I * R.

What is the energy consumption in kilojoules of a 15-watt device running for 30 minutes?

First, convert the power to watt-minutes (15 watts * 30 minutes = 450 watt-minutes). Then, convert watt-minutes to kilojoules (450 watt-minutes / 60 = 7.5 kilojoules, since 1 watt-minute equals 1/60th of a kilojoule).

How do you find the total resistance in a parallel circuit when the individual resistances and the voltage across the circuit are known?

In a parallel circuit, the total resistance (Rt) can be found using the formula 1/Rt = 1/R1 + 1/R2 + ... + 1/Rn, where R1, R2, ..., Rn are the individual resistances. If the voltage is known, you can also calculate the current through each resistor and then use the above formula.

What is the formula to calculate the power consumption of an electrical device?

The power consumption (P) of an electrical device is calculated using the formula P = V * I, where V is the voltage and I is the current. Alternatively, if the resistance (R) is known, it can also be calculated using P = V^2 / R or P = I^2 * R.

Outlines

00:00

🔌 Electrical Measurement and Ohm's Law Application

This paragraph discusses the process of reading an electric current from a scale diagram and calculating the current using the formula: measured current = (scale reading / maximum scale) * maximum current. It then moves on to explain the measurement of resistance using a voltmeter with a resistance of 1 kilo-ohm and an ammeter with a resistance of 1 ohm. The key concept is applying Ohm's law to find the unknown resistance (Rx) using the formula Rx = Vx / Ix, where Vx is the voltage across the unknown resistance and Ix is the current through it. The paragraph also involves the application of Kirchhoff's current law to ensure the conservation of charge at a junction in a circuit.

05:00

💡 Power and Energy Calculations for Lighting and Heating Devices

The second paragraph delves into the calculation of power and energy for a light bulb and a heating device. It starts with a 60-watt light bulb operating at 220 volts and calculates the actual power consumption when the voltage is different from the rated voltage, using the formula P = V^2 / R. The paragraph then calculates the energy consumption of the light bulb over a period of 30 minutes using the formula E = P * t. Subsequently, it discusses the power rating of a heating device and the required length of a wire with a resistance of 25 ohms per meter, given a voltage of 125 volts and a power rating of 200 watts. The final calculation determines the length of the wire needed using the formula for resistance per unit length and the total resistance required.

10:07

📏 Calculation of Wire Length for a Heating Element

This paragraph focuses on the calculation of the wire length needed for a heating element with a resistance of 25 ohms per meter. It uses the previously calculated resistance and power values to determine the length of the wire required for the heating element to operate at the desired power. The calculation involves dividing the total resistance needed by the resistance per meter of the wire to find the length. The paragraph also simplifies the fraction obtained from the division to provide a clear and concise answer for the wire length in centimeters.

Keywords

💡Ammeter

An ammeter is an instrument used to measure the electric current in a circuit. In the video, it is mentioned alongside a voltmeter, and the script discusses how to calculate resistance using these tools. The ammeter's reading is crucial for applying Ohm's law to find the unknown resistance in a circuit, as seen when the script calculates the total current and uses it to find the value of 'RX'.

💡Voltmeter

A voltmeter is an instrument used to measure the electric potential difference between two points in an electrical circuit. In the context of the video, a voltmeter with an internal resistance of 1 kilo Ohm is used to measure voltage across an unknown resistance 'X'. The script uses the voltmeter's reading of 5 volts to apply Ohm's law and calculate the resistance 'RX'.

💡Resistance (R)

Resistance is a property of materials that opposes the flow of electric current. The script discusses measuring resistance using a voltmeter and ammeter, applying Ohm's law (V = IR). The concept is central to the video as it guides the viewer through calculating the unknown resistance 'RX' using the measured voltage and current.

💡Ohm's Law

Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them (V = IR). The video script applies this law to calculate the unknown resistance 'RX' using the measured voltage and current from the voltmeter and ammeter, respectively.

💡Kirchhoff's Laws

Kirchhoff's Laws are fundamental laws of electrical circuits, which include the current law (the sum of currents in a network of conductors meeting at a point is zero) and the voltage law (the algebraic sum of the potential differences in any closed circuit is zero). The script mentions these laws when discussing how to calculate the total current in a parallel circuit to find the unknown resistance 'RX'.

💡Wattage

Wattage is a measure of power, defined as the rate at which electrical energy is converted into another form of energy. The video script refers to a light bulb with a wattage of 60W and discusses how the actual power consumption changes when the voltage across the bulb differs from its rated voltage. This is an example of how wattage can vary with different voltages.

💡Voltage (V)

Voltage, also known as electric potential difference, is the driving force that pushes electric charge through a circuit. In the video, voltage is discussed in the context of measuring resistance and calculating power consumption. The script uses the voltage measured by the voltmeter to apply Ohm's law and find the resistance 'RX'.

💡Current (I)

Electric current is the flow of electric charge through a conductor. The script discusses measuring current using an ammeter and how it relates to resistance and voltage through Ohm's law. The current measured (25 milliamperes) is used to calculate the unknown resistance 'RX' in the circuit.

💡Energy (E)

Energy in the context of the video refers to electrical energy, which is the work done by an electric current. The script calculates the energy consumed by a light bulb using the formula E = P * t, where P is power in watts and t is time in seconds. This calculation is used to find the energy used by the bulb over 30 minutes.

💡Power (P)

Power is the rate at which work is done or energy is transferred. In the video, power is discussed in relation to the wattage of a light bulb and how it changes with different voltages. The script shows how to calculate the actual power consumption of a bulb when the voltage across it is different from its rated voltage.

💡Electrical Circuit

An electrical circuit is a path through which electric current flows. The video script discusses various types of circuits, including series and parallel circuits, and how they relate to the measurement of resistance and voltage. The understanding of circuits is essential for applying Ohm's law and Kirchhoff's laws to solve the problems presented in the script.

Highlights

Calculation of measured current using a scale from an electric current image.

Explanation of maximum scale and current measurement with a 1-ampere maximum current.

Determination of the actual measured current as 1/3 ampere using the given scale and maximum current.

Introduction to measuring resistance using a voltmeter with a 1 kilo-Ohm and an ammeter with a 1-Ohm resistance.

Setup for measuring resistance X using a parallel circuit configuration.

Readings of 5 volts and 25 milliamperes are used to calculate the resistance X.

Application of Ohm's law to find the resistance X using the formula RX = V/I.

Use of Kirchhoff's current law to determine the total current in the circuit.

Calculation of the current through the voltmeter and ammeter to find the total current.

Determination of the resistance X using the total current and voltage across the voltmeter.

Calculation of the resistance X as 50 Ohms using the given voltage and current values.

Analysis of a light bulb with a 60-watt rating and a 220-volt specification.

Adjustment of power calculation for a light bulb when connected to a different voltage.

Calculation of energy consumption for the light bulb when operating for 30 minutes.

Introduction to calculating the required length of a heating element wire with a 200-watt power rating.

Determination of the wire length needed for the heating element based on resistance and voltage.

Final calculation of the wire length as 3.125 meters for the heating element.

Transcripts

Hai yang soal yang sederhana ini ya yang

pertama pembacaan arus listrik dari

gambar dibawah ini kita perhatikan

gambar dibawah ini ini jarum menunjukkan

diangkat 30 ini adalah skala yang

terukur kemudian 90 ini adalah skala

maksimum dan ini eh kabelnya mencolok

pada arus maksimum 1 ampere ya kita bisa

menghitung besarnya arus yang terukur i5

dengan skala yang terbaca ya dibagi

skala maksimum dikali arus maksimum jadi

ini sama dengan skala yang terbacanya

disini 30 kalau maksimumnya disini 90

dikali arus maksimum nya disini 1ampere

jadiin = 1/3 ampere dah Selanjutnya

cce untuk nomor dua ya selanjutnya kita

lihat kesini Perhatikan gambar di bawah

di samping ini di bawah ya voltmeter

memiliki hambatan 1 kilo Ohm ampere M

memiliki hambatan 1 Ohm kedua alat ini

digunakan untuk mengukur hambatan X

menggunakan rangkaian seperti gambar

pada feat terbaca 5volt padaa terbaca 25

mili ampere besarnya hambatan x adalah

di sini diketahui voltmeter memiliki

hambatan 1 kg kita kasih nama disini

berarti disitu ada rr1 kilo Ohm detik di

sini ada hambatan kemudian ampere M

memiliki hambatan berarti disini ini ada

er amperemeter satu Om dan voltmeter

K5 fold batik tegangan ujung-ujung sini

ini 5 volt dan ampere meter terbaca 25

mili ampere disini adalah 25 mili ampere

yang ditanyakan adalah besarnya hambatan

r x ya RX yang ditanyakan adalah rxr itu

= V dibagi Iya menurut ke hukum Om VX

dibagi x VX ya Ini karena rangkaiannya

paralel ya titik-titik ini ini

ujung-ujung voltmeter ujung-ujung

voltmeter sama dengan tegangan VX jadi

VX sudah diketahui fixnya = 5 volt

kemudian disini ada snack ini yang 25

mili ampere ini bukan YKS tapi ini

adalah harus total ya nabati Kita harus

mencari x-men di sini ya ekspedisi ini

berapa harus total kita gunakan hukum2

om Eh hukum 2 Kirchoff i

harus yang masuk itu sama dengan arus

yang keluar ke satu titik misalnya

titiknya di sini titik O berarti arus

yang masuk ke titik O itu adalah arus

maksimum ini ya atau boleh juga arus

yang keluar harus yang keluar kesini

adalah I yang mengalir ke ampere meter

kemudian di sini ada I X dan di sini ada

i v arus yang masuk itu adalah IV dan V

X jadi Ive tambahi X gitu ya sama dengan

arus yang keluarnya adalah yang 25 inii

total ip-nya kita gunakan hukum Om lagi

ya Ih sama dengan Viper er FTV expert

efek eh sorry disitu Vivia seri ini

tegangan untuk voltmeter ngerti ini V

voltmeter dibagi vs lagi deh dibagi er

hot m gitu ya ditambahi FC mau kita cari

= i

leave itu adalah 5volt dibagi Rp nya itu

adalah satu kilo Ohm jadi 1000 m

ditambah qxc kita mau cari = I ini 25

Mili 25/1000 ya 25 milik ah Kita cari

sekarang kita cari dulu Berarti IC nya

itu sama dengan 25/1000 dikurangi 5/1000

= 20 per 1000 Ampere atau 25000000000 20

mili ampere udah sekarang kita masukkan

ke RX RX = V Xperia E X = voltmeter tadi

5 dibagi Yes sajalah 20100mah ke atas

jadi 5000 per 20 =

50 Om selanjutnya nomor tiga pada sebuah

lampu pijar tertulis 60watt 6 What itu

satuan untuk daya daya lampu pijar

kemudian ini tegangannya 220volt V lampu

pijar nya 220volt lampu terpasang pada

tegangan ini tegangan yang dipasang V

selama 30 menit berarti t maka besar

daya lampu dan energi yang timbul daya

itu PN Ergi itu W atau Eya kita cari

dulu kayaknya P pada p yang digunakan

itu tidak sama dengan 60watt Kenapa

karena tegangannya itu dipasang pada

tegangan yang berbeda ya Jadi kita harus

mencari dulu disini apa yang tidak

berubah ketika tegangannya 220 dayanya

60watt apa yang tidak berubah disitu

padahal

Hai itu adalah hambatannya truk kita

lihat P itu = v kuadrat er jadi ini P

lampu er lampu ya gitu nah ketika

220volt dayanya 60watt haba tanyakan

konstan jadi kita bisa cari er lampunya

itu sama dengan file kuadrat per PL atau

sama dengan 220/50 220 kuadrat gitu ya

maka daya yang digunakan up aksen ya ada

yang digunakan pada tegangan 110v itu V

yang 110 cord dibagi RL jadi 110 kuadrat

per er elne itu tadi adalah 220 kuadrat

pernah 60 naik ke atas ya nih sama

dengan satu 11/22 1/2 kuadratnya 1/2

kuadrat kali 60 jadi

empat kali 60 = 15 lewat Nah sekarang

kita tentukan energinya energi itu

adalah PK Lite ya energi x = p * t atau

boleh juga ya kayaknya tadi udah ada

15watt pengennya 30 menit buat dalam

second w30 kali 60 jadi sama dengan

berapa nih 15 kali dua 3030 ikan 15 Aduh

ini rada lolang itunya ya 30 kali dua ya

Jadi ini tiga kali tiga kali tiga

Rp27.000 jual atau sama dengan 27

kilojoule casual terakhir seseorang ini

buat sebuah alat pemanas 200watt 200watt

itu berarti P lagi ya dari suatu kawat

yang mempunyai hambatan 25 Ohm tiap

meter diketahui ini 25 Om tiap meter

berarti ini Rp relnya ya er pr-nya 25 Om

permeter bila hambatan kawat dianggap

konstan dan tegangan yang dipakai 125

volt maka panjangnya kawat yang

diperlukan adalah maksudnya disini

hambatan jenis ya hambatan jenis kawat

nya konstan maka panjangnya kawat yang

diperlukan adalah ini digunakan pada

tegangan V ya Nah kita lihat p sama

dengan v kuadrat per er jadi r-nya = v

kuadrat perfect venue tadi 125 kuadrat

per kayaknya adalah 200 jadi ini sama

dengan 125 kali 125/250 Biarkan saja

dulu jangan

dihitungnya Mas sekarang di sini yang

ditanyakan adalah panjang kawat yang

diperlukan kita tahu kalau er itu sama

dengan ro elber a Jadi kalau hambatan

jenis kawat nya tetap luas penampang

udah pasti sama ya maka alternatifking4d

banding dengan l gitu ya Jadi kalau ada

ini tadi 25 sore ini tadi ada 25 Om per

meter per meternya itu 25 Om sekarang

kita butuh 125 Kalisat 25/200 sudah kita

masukkan aja RL itu sama dengan 25 Om

sama dengan 125 kali 125 R 200 gitu ya

jadi

Hai r-nya airnya kita kalikan ini 25l ya

25 l = 125k Lee 1-25 per 206 kita

sekarang kali silang jadi l-nya sama

dengan kita bagi dengan 25 kiri-kanan ya

kiri kanan kita bagi dengan 25 25

websites 25125 bagi 25 itu adalah lima

200 bagi lima itu adalah 200 dibagi lima

berapa 200 dibagi lima itu adalah 40 Ya

jelas sebagai 5/40 habis ini jadi 125

per 40 kita Sederhanakan dibagi lima itu

25 per delapan

Mbak 25/8 itu adalah ketiga ya 3,8 25

bagi delapan 3,6 tanyakan 1 10 ke-8

3,125

Hai atau berapa 312 koma 5 cm