Ohm's Law and Joule's Law Quiz

Heat produced is directly proportional to the square of current, resistance, and the time the current flows.

Current can be calculated using the formula $I = \frac{V}{R}$.

The current is approximately 3.82 A.

<p>The resistance is approximately 57.60 Ω.</p> Signup and view all the answers

<p>The current is approximately 1.64 A.</p> Signup and view all the answers

<p>The resistance is approximately 134.15 Ω.</p> Signup and view all the answers

<p>The current is 5 A.</p> Signup and view all the answers

<p>The voltage is 20 V.</p> Signup and view all the answers

<p>Joule's law allows us to determine how much heat is generated based on current, resistance, and time.</p> Signup and view all the answers

<p>Power is the product of voltage and current, given by the formula $P = VI$.</p> Signup and view all the answers

<p>Joule's law states that heat produced by a resistor is directly proportional to the square of the current, the resistance, and the time for which the current flows. This means that increasing the current or resistance, or extending the time, will result in more heat being produced.</p> Signup and view all the answers

<p>Ohm's law is used to determine the current (I = V/R) which is then substituted into the equation for Joule's law to calculate the heat produced. This shows that heat production depends on the voltage, resistance, and time.</p> Signup and view all the answers

<p>The maximum setting utilizes more power, resulting in a higher current draw. This is because a higher power output necessitates a larger current flow.</p> Signup and view all the answers

<p>By adjusting the voltage supply, you can control the current flowing through the iron, which directly influences the heat output according to Joule's law. A higher voltage leads to a higher current and thus more heat.</p> Signup and view all the answers

<p>Increasing resistance while keeping the voltage constant will decrease the current flow, resulting in a decrease in heat production. A higher resistance means less current flows for the same voltage.</p> Signup and view all the answers

<p>It provides a quantitative relationship between electrical parameters and the heat produced due to the flow of current through a resistor. This allows us to predict and control heat generated in various electrical applications.</p> Signup and view all the answers

<p>Rearranging the power equation (P = VI) to find the current (I = P / V), then using Ohm's law (R = V / I) to calculate the resistance.</p> Signup and view all the answers

<ol> <li>Double the current flowing through the resistor by changing the resistance to one-half of the original value.</li> <li>Double the time the current flows through the resistor.</li> </ol> Signup and view all the answers

<p>Examples include electrical heating devices like toasters, ovens, and electric kettles, where the heat produced is directly controlled by the current flow and resistance. This also applies to electrical components like light bulbs, where the heat generated is a byproduct of light production.</p> Signup and view all the answers

<p>The heat produced increases proportionally to the increased time the current flows. The longer the current flows, the more energy is dissipated as heat.</p> Signup and view all the answers

<p>The heat produced is directly proportional to the time, meaning that increasing the time will result in more heat generated.</p> Signup and view all the answers

<p>The current can be calculated using the formula $I = \frac{P}{V}$.</p> Signup and view all the answers

<p>Power consumption increases with the square of the current while voltage remains unchanged, as described by $P = VI$.</p> Signup and view all the answers

<p>Changing settings may alter the current, which in turn affects the heat produced as it is directly proportional to $I^2$.</p> Signup and view all the answers

<p>You would rearrange Joule's law to find resistance using $R = \frac{H}{I^2 t}$, with current calculated from heat.</p> Signup and view all the answers

<p>Resistance inversely affects current, meaning higher resistance leads to lower current for a fixed voltage, as given by $I = \frac{V}{R}$.</p> Signup and view all the answers

<p>Voltage directly affects the amount of power consumed, calculated as $P = VI$, which feeds into the amount of heat generated.</p> Signup and view all the answers

<p>You would use Joule's law, H = $I^2Rt$, to find the heat produced in that resistor.</p> Signup and view all the answers

<p>Joule's law indicates maximum allowable current and resistance to prevent excessive heat buildup, guiding safe designs.</p> Signup and view all the answers

<p>Increased current boosts heat production exponentially ($I^2$), which can reduce energy efficiency due to losses and wasted heat.</p> Signup and view all the answers

<p>The cord has a lower resistance than the heating element, resulting in less heat generation and thus it does not glow.</p> Signup and view all the answers

<p>The heat generated is 4800000 J, using the formula $Q = V imes I imes t$ where $I = \frac{Q}{t}$.</p> Signup and view all the answers

<p>The heat developed is 1500 J, using the formula $H = I^2Rt$.</p> Signup and view all the answers

<p>An electric bulb uses the heating effect to heat the filament until it glows and emits light.</p> Signup and view all the answers

<p>Tungsten is used because it has a high melting point, allowing it to withstand the high temperatures without melting.</p> Signup and view all the answers

<p>A fuse protects the circuit by breaking the connection when the current exceeds a predefined limit.</p> Signup and view all the answers

<p>Electrical appliances like irons and toasters convert electrical energy into heat for practical cooking or ironing tasks.</p> Signup and view all the answers

<p>Filling the bulb with inert gas helps to prolong the filament's life by reducing oxidation, thus maintaining higher temperatures.</p> Signup and view all the answers

<p>Higher voltage leads to increased current, resulting in more heat produced in a conductor according to Joule's law.</p> Signup and view all the answers

<p>Thermal isolation minimizes heat loss to the surroundings, ensuring more efficient functioning of the heating element.</p> Signup and view all the answers

<p>An electric kettle uses the heating effect of electric current to heat water rapidly by passing current through a resistive heating element, converting electrical energy into thermal energy.</p> Signup and view all the answers

<p>Fuses contain a thin wire that melts and breaks the circuit when the current exceeds a certain level, preventing overheating or damage to appliances.</p> Signup and view all the answers

<p>Tungsten is used for electric bulb filaments because it has a high melting point, allowing it to withstand high temperatures without melting.</p> Signup and view all the answers

<p>Inert gases in electric bulbs reduce evaporation of the filament material, prolonging its life and maintaining brightness.</p> Signup and view all the answers

<p>Thermal insulation minimizes heat loss, allowing electric heating elements to concentrate energy effectively for heating purposes.</p> Signup and view all the answers

<p>In an electric bulb, electrical energy flows through the filament, causing it to heat up and emit light due to incandescence.</p> Signup and view all the answers

<p>An appliance may overheat, potentially leading to failure, damage, or even fire if the excess current is not interrupted.</p> Signup and view all the answers

<p>The heating effect can reduce energy efficiency, as energy lost as heat is not used for the intended electrical work in the circuit.</p> Signup and view all the answers

<p>Considering the heating effect is vital to ensure components can handle heat without deterioration, maintaining performance and safety.</p> Signup and view all the answers

<p>Joule's heating allows for efficient thermal management in appliances, enabling innovations in cooking, heating, and lighting technologies.</p> Signup and view all the answers

<p>Joule's law states that the heat produced in a conductor is directly proportional to the square of the current, the resistance of the conductor, and the time for which the current flows. In an electric heater, the heating element has a high resistance, causing a significant amount of heat to be generated when current flows through it.</p> Signup and view all the answers

<p>The high melting point of tungsten allows it to withstand the intense heat generated when electric current flows through it. This prevents the filament from melting or breaking down, ensuring the bulb's longevity and providing a sustained light source.</p> Signup and view all the answers

<p>The cord of an electric heater is made of a material with lower resistance compared to the heating element. This means that the cord generates less heat for the same current, resulting in a much lower temperature and preventing it from glowing.</p> Signup and view all the answers

<p>A fuse is a safety device designed to protect electrical circuits from excessive current flow. It acts as a weak link in the circuit, melting and breaking the circuit when the current exceeds a predetermined limit, preventing damage to appliances or even fire hazards.</p> Signup and view all the answers

<p>Filling electric bulbs with chemically inactive gases like nitrogen and argon delays the evaporation of the filament. These gases prevent oxidation and prolong the filament's life, ensuring a longer-lasting and more efficient bulb.</p> Signup and view all the answers

<p>An electric kettle uses a heating element with high resistance immersed in water. When the current passes through the heating element, it generates a considerable amount of heat, transferring it to the surrounding water, thus heating it efficiently.</p> Signup and view all the answers

<p>Joule's law explains the operation of these appliances by establishing a relationship between heat production and the electric current, resistance, and time, resulting in varying levels of heating for various uses. For instance, high resistance heating elements in toasters generate more heat quickly for browning toast, while lower resistance elements in electric irons provide gentler, controlled heating for ironing fabrics.</p> Signup and view all the answers

<p>Thermal isolation ensures that the heat generated by a heating element is directed primarily toward the object or area being heated. By minimizing heat loss to the surrounding environment, thermal insulation improves the efficiency of the heating process.</p> Signup and view all the answers

<p>The heating effect of current is essential for many electrical components, but can also pose safety risks and affect the overall performance of a circuit. During the design process, it's crucial to ensure that components can handle the expected heat generated without failure, potential overheating, or fires. Safe operating temperatures and appropriate insulation are critical considerations.</p> Signup and view all the answers

<p>The amount of heat generated by a resistor is directly proportional to the square of the applied voltage. Higher voltage results in more heat. Resistance inversely affects heat production. Higher resistance decreases current flow, reducing heat generation. However, resistance ultimately determines the amount of heat produced for a given voltage.</p> Signup and view all the answers

<p>The SI unit of electric power is the watt (W), defined as the power consumed by a device carrying 1 A of current at a potential difference of 1 V.</p> Signup and view all the answers

<p>The kilowatt is used when measuring electric power in larger quantities, equal to 1000 watts.</p> Signup and view all the answers

<p>A watt hour (W h) is the energy consumed when 1 watt of power is used for 1 hour.</p> Signup and view all the answers

<p>Power can be calculated using the formula P = VI, where P is power, V is voltage, and I is current.</p> Signup and view all the answers

<p>The commercial unit of electric energy is commonly known as the kilowatt hour (kW h).</p> Signup and view all the answers

<p>Many people wrongly think that electrons are consumed in the circuit; instead, we pay for the energy to move them.</p> Signup and view all the answers

<p>Using 1 kWh means that 1000 watts of power has been consumed over one hour.</p> Signup and view all the answers

<p>The watt is considered small, so larger units like kilowatts are often used for energy measurement.</p> Signup and view all the answers

<p>For a bulb connected to 220 V with a current of 0.50 A, power is P = VI = 220 V × 0.50 A = 110 W.</p> Signup and view all the answers

<p>Power can be expressed as P = I²R or P = V²/R, showing how it relates to current and resistance.</p> Signup and view all the answers

<p>Electric power (P) is the rate at which electrical energy is consumed or dissipated in a circuit. It is directly proportional to both voltage (V) and current (I). The relationship is expressed by the equation: <strong>P = VI</strong>.</p> Signup and view all the answers

<p>The standard unit for electric power is the watt (W). One watt represents the power consumed by a device when conducting one ampere of current at a potential difference of one volt. The unit for electric energy is the watt-hour (Wh), which measures the energy consumed when one watt of power is used for one hour. Since energy is the product of power and time, one watt-hour is equivalent to 3600 joules (J).</p> Signup and view all the answers

<p>The kilowatt-hour (kWh) is used as the commercial unit for electrical energy consumption because it represents a larger and more practical unit for measuring household or industrial electricity usage. It is equal to 1000 watts of power consumed over one hour, which is a significant amount of energy compared to the smaller unit of watt-hour.</p> Signup and view all the answers

<p>Joule's law of heating describes the relationship between heat generated, current, resistance, and time in a conductor. It states that the heat produced in a conductor is directly proportional to the square of the current, the resistance of the conductor, and the time for which the current flows. This law is crucial in understanding how electrical appliances, such as heaters, irons, and toasters, generate heat.</p> Signup and view all the answers

<p>The power consumed by the heater can be calculated using the formula P = V²/R. Substituting the given values, we get P = (220 V)² / 10 Ω = 4840 W. Therefore, the electric heater consumes 4840 watts (or 4.84 kilowatts) of power.</p> Signup and view all the answers

<p>Tungsten has a very high melting point compared to other metals, making it ideal for use in electric bulb filaments. When electricity flows through the filament, it heats up to a very high temperature, causing it to glow. Tungsten's high melting point prevents it from melting and burning out prematurely, ensuring a longer lifespan for the bulb.</p> Signup and view all the answers

<p>A fuse is a safety device designed to protect electrical circuits from overcurrents. It consists of a thin wire that melts and breaks the circuit when the current flowing through it exceeds a predetermined limit. This prevents damage to the circuit and connected appliances from overheating due to excessive current.</p> Signup and view all the answers

<p>Electric power is the rate at which electrical energy is consumed or dissipated in a circuit, while electric energy is the total amount of energy consumed over a period of time. Power is measured in watts (W), while energy is measured in watt-hours (Wh) or kilowatt-hours (kWh). For example, a 100-watt bulb consumes 100 watts of power when turned on, while a 1-kWh meter measures the total energy consumed by an entire household over a given period.</p> Signup and view all the answers

<p>The energy consumed can be calculated by multiplying the power by the time. In this case, the energy consumed is 1000 W × 2 hours = 2000 Wh. To convert this to kWh, we divide by 1000, giving us 2000 Wh / 1000 = 2 kWh. Therefore, the iron consumes 2 kWh of energy.</p> Signup and view all the answers

<p>Many electrical appliances, like heaters, irons, and toasters, utilize the heating effect of electric current for their operation. When electric current flows through a conductor, the resistance of the conductor causes heat to be generated. By employing materials with specific resistances and designing the circuit appropriately, these appliances convert electrical energy into heat energy. For instance, an electric heater uses a high-resistance heating element to produce heat, while a toaster utilizes a nichrome wire coil to toast bread.</p> Signup and view all the answers

<p>Electric power is defined as $P = VI$, where $P$ is power, $V$ is voltage, and $I$ is current.</p> Signup and view all the answers

<p>The commercial unit of electric energy is kilowatt hour (kW h), which is equivalent to 1000 watt hours (W h).</p> Signup and view all the answers

<p>It signifies that one watt is the power consumed by a device with a current of 1 ampere operating at a potential difference of 1 volt.</p> Signup and view all the answers

<p>It consumes 110 watt hours (W h) of energy after operating for 1 hour.</p> Signup and view all the answers

<p>The formula is $P = I^2R$, where $P$ is power, $I$ is current, and $R$ is resistance.</p> Signup and view all the answers

<p>Electrons are not consumed; we pay for the energy required to move them through electrical devices.</p> Signup and view all the answers

<p>The energy consumed is 360 kW h, costing Rs 1080.</p> Signup and view all the answers

<p>It can be represented by the equation $P = V^2/R$, highlighting the relationship between voltage, power, and resistance.</p> Signup and view all the answers

<p>The current is calculated using $I = P/V$, giving $I = 840 W / 220 V = 3.82 A$.</p> Signup and view all the answers

<p>The kilowatt hour is used because it provides a practical scale for the amount of energy consumed over time in residential settings.</p> Signup and view all the answers

<p>$W = V \times I \times t$</p> Signup and view all the answers

<p>Ampere</p> Signup and view all the answers

<p>Watt</p> Signup and view all the answers

<p>Kilowatt-hour (kWh)</p> Signup and view all the answers

<p>Directly proportional</p> Signup and view all the answers

<p>Inversely proportional</p> Signup and view all the answers

<p>The potential difference across the ends of a resistor is directly proportional to the current through it, provided its temperature remains the same.</p> Signup and view all the answers

<p>The sum of their individual resistances</p> Signup and view all the answers

<p>$\frac{1}{Rp} = \frac{1}{R1} + \frac{1}{R2} + \frac{1}{R3} + ...$</p> Signup and view all the answers

<p>The power of the current</p> Signup and view all the answers

<p>The unit of electrical power is the watt (W). One watt of power is consumed when 1 ampere of current flows at a potential difference of 1 volt.</p> Signup and view all the answers

<p>In a series connection, resistors are connected end-to-end, and the equivalent resistance is the sum of individual resistances. In a parallel connection, resistors are connected side-by-side, and the reciprocal of the equivalent resistance is the sum of the reciprocals of individual resistances.</p> Signup and view all the answers

<p>Resistance opposes the flow of current in a conductor. Higher resistance means less current will flow for a given voltage.</p> Signup and view all the answers

<p>Resistance is directly proportional to the length of the conductor, inversely proportional to its cross-sectional area, and also depends on the material. Longer conductors, smaller cross-sectional areas, and materials with higher resistivity result in greater resistance.</p> Signup and view all the answers

<p>The commercial unit of electrical energy is the kilowatt-hour (kWh). 1 kWh equals 3.6 × 10^6 joules.</p> Signup and view all the answers

<p>Potential difference, measured in volts, represents the difference in electrical potential energy between two points in a circuit. It drives the flow of electric current, with a higher potential difference leading to a stronger flow of current.</p> Signup and view all the answers

<p>Understanding the heating effect is crucial for safety, designing efficient appliances, and ensuring proper operation of electrical systems. Excessive heat can damage components, cause fires, and even lead to explosions. Designing appliances to minimize heat loss improves energy efficiency.</p> Signup and view all the answers

<p>Joule's law states that the heat produced in a resistor is directly proportional to the square of the current, the resistance, and the time. The power dissipated in a resistor is the rate at which heat is produced, which is also proportional to the square of the current and the resistance.</p> Signup and view all the answers

<p>Electric current is the flow of electric charge, typically carried by electrons, through a conductor. The conventional direction of current is opposite to the direction of electron flow.</p> Signup and view all the answers

<p>The total energy consumed by a refrigerator is calculated by multiplying its power rating (in watts), the daily usage time (in hours), and the number of days of operation. This gives the energy consumed in watt-hours (Wh), which can then be converted to kilowatt-hours (kWh).</p> Signup and view all the answers

<p>The cost of operating a refrigerator is calculated by multiplying the total energy consumed (in kWh) by the cost per kilowatt-hour (kWh). This effectively translates the electrical energy consumption into a monetary value.</p> Signup and view all the answers

<p>The physical quantity that determines the rate at which energy is delivered by an electric current is <em>power</em>. Power is the rate at which work is done or energy is transferred, and it is directly proportional to the current flowing through a circuit, meaning a higher current results in a higher power output.</p> Signup and view all the answers

<p>Ohm's law states that the potential difference (V) across a conductor is directly proportional to the current (I) flowing through it, provided the temperature remains constant. The proportionality constant is called the resistance (R). Mathematically, V = IR. The units of measurement for voltage are volts (V), for current are amperes (A), and for resistance are ohms (Ω).</p> Signup and view all the answers

<p>The power consumed by an electric motor can be determined using the formula: Power (P) = Voltage (V) x Current (I). This means that the power consumed is directly proportional to both the voltage applied and the current flowing through the motor. Therefore, higher voltage and higher current result in higher power consumption.</p> Signup and view all the answers

<p>The energy consumed by an electric motor over time is calculated by multiplying the power it consumes (in watts) by the time it operates (in hours). This gives the energy consumption in watt-hours (Wh), which can then be converted to kilowatt-hours (kWh).</p> Signup and view all the answers

<p>The resistance of a conductor is influenced by three main factors: 1) <strong>Length:</strong> Longer conductors have higher resistance. 2) <strong>Cross-sectional area:</strong> Conductors with larger cross-sectional areas have lower resistance. 3) <strong>Material:</strong> Different materials have different inherent resistances (resistivity). The resistance of a conductor directly proportional to its length and inversely proportional to its cross-sectional area. Materials with higher resistivity lead to higher resistance.</p> Signup and view all the answers

<p>In a series combination of resistors, the equivalent resistance (R_eq) is the total resistance of the circuit. It is calculated by adding the individual resistances of all resistors in the series connection: R_eq = R_1 + R_2 + R_3 + ... . The equivalent resistance for the combination is always higher than the largest individual resistance in the series.</p> Signup and view all the answers

<p>In a parallel combination of resistors, the reciprocal of the equivalent resistance (1/R_eq) is equal to the sum of the reciprocals of individual resistances: 1/R_eq = 1/R_1 + 1/R_2 + 1/R_3 + ... . The equivalent resistance for the parallel combination is always lower than the smallest individual resistance in the set.</p> Signup and view all the answers

<p>Electrical power is the rate at which electrical energy is transferred or used. It is the product of voltage (V) and current (I) in a circuit: Power (P) = Voltage(V) x Current (I). Energy is the total amount of power consumed over a certain time. Electrical power is measured in watts (W), and energy is measured in joules (J) or kilowatt-hours (kWh).</p> Signup and view all the answers

Heat produced in a resistor is proportional to current squared, resistance, and time.

The flow of electric charge, measured in Amperes (A).

Opposition to electric current, measured in Ohms (Ω).

The rate at which energy is consumed or produced, measured in Watts (W).

Voltage (V) is equal to the current (I) times the resistance (R).

Energy produced in a resistor due to current flow, measured in Joules (J).

The electric potential difference between two points, measured in Volts (V).

The highest power consumed by an appliance when running at full heat.

The lowest power consumed by an appliance when running at lower heat.

The voltage across a resistor calculated using current and resistance.

Heat produced is proportional to current squared, resistance, and time.

Heat is produced in a resistor while current flows through it.

Power is the product of voltage and current (P = VI).

Current can be calculated using power and voltage (I = P/V).

Resistance can be calculated using voltage and current (R = V/I).

Heat produced is measured in Joules (H) and calculated via Joule's Law.

The voltage across a resistor can be derived from current and resistance.

An electric iron consumes 840 W at maximum heating rate.

An electric iron consumes 360 W at minimum heating rate.

For a 4 Ω resistor producing 100 J heat, current is calculated as I = √(H/Rt).

H = I² Rt; calculates heat produced in a resistor.

P = VI; used to determine power based on voltage and current.

Maximum current calculation when heating at full power.

Minimum current calculation when heating at low power.

R = V/I; calculates resistance using voltage and current values.

Heat produced over time in a resistor, measured in J/s.

The potential difference V across a resistor, calculated as V = IR.

I = √(H/Rt); used to determine current for given heat, resistance, and time.

Examples illustrating how to find current and resistance based on power measurements.

Heat generation in a conductor due to electric current flow.

Heat produced in a resistor is caused by electric current according to Joule's law.

Useful devices utilizing heat generated include irons, toasters, and kettles.

Thin wire in light bulbs that emits light when heated, usually made of tungsten.

Temperature at which tungsten can melt, around 3380°C.

A safety device that breaks the circuit if current exceeds a safe level.

Keeping the filament insulated to prevent heat loss for efficiency.

Uses Joule's heating to quickly boil water through electric current.

Appliance utilizing Joule's heating to toast bread.

Inert gases like nitrogen and argon fill to prolong filament life.

The cord does not glow because it has higher resistance than the heating element which converts energy to heat instead of light.

Heat can be computed using the formula H = QV where Q is charge and V is voltage.

Devices such as irons, toasters, and electric kettles utilize the heat produced by electric current for practical uses.

The thin wire that emits light when heated, typically made of tungsten due to its high melting point.

A safety component in electric circuits which stops the flow of excessive current to prevent damage.

Electric iron with a specific resistance and current generates heat based on the formula H = I²R.

An electric iron generates heat based on its resistance and the current passing through it.

The wire in light bulbs made from tungsten, chosen for its high melting point.

H = QV, where Q is charge and V is voltage, used to compute heat generated.

Material used to thermally isolate the filament in electric bulbs.

Devices that utilize Joule's heating include electric irons, toasters, and kettles.

The rate at which electric energy is consumed in a circuit, calculated as P = VI.

The SI unit is watt (W), representing power consumption of 1 A at 1 V.

A larger unit of power equal to 1000 watts, commonly used in appliances.

Energy consumed when 1 watt of power is used for 1 hour.

A commercial unit of energy equivalent to 1000 watt hours.

Consumers pay for energy to move electrons, not the electrons themselves.

Power can be calculated using different formulas: P = I²R or P = V²/R.

For a 220 V generator with 0.50 A current, power is P = VI = 110 W.

Cost of energy can be calculated by multiplying power usage by time and rate.

The total energy consumed in a circuit, measured in joules (J).

The SI unit of electric power is watt (W), defined as 1 V × 1 A.

Cost can be calculated by multiplying power usage by time and rate (in kWh).

For a 220 V generator with 0.50 A current, power is P = VI = 110 W.

We pay for the energy to move electrons, not the electrons themselves.

Total energy a refrigerator uses in 30 days is 96 kWh.

Cost to run a refrigerator for 30 days is Rs 288.00.

Potential difference is the voltage across a cell to set electrons in motion.

Electric current is the flow of charge, measured in Amperes (A).

The voltage across a resistor is proportional to the current; V = IR.

Energy in a resistor is given by W = V × I × t.

One watt is consumed when 1 A flows at 1 V.

In series, total resistance is the sum of individual resistances.

Total energy used by a device over time, measured in kWh.

Flow of electric charge through a conductor, measured in Amperes (A).

Total resistance in parallel calculated as 1/Rp = 1/R1 + 1/R2 + ...

The energy consumed by a refrigerator in 30 days is 96 kWh.

Operating a refrigerator for 30 days costs Rs 288.00.

The power of a motor taking 5 A from a 220 V line is 1100 W.

A stream of electrons moving through a conductor constitutes electric current.

The SI unit of electric current is Ampere (A).

Resistance opposes the flow of electric current, measured in Ohms (Ω).

The unit of power is watt (W); one watt is 1 A flowing at 1 V.