Electric Power - AP Physics 2
Card 1 of 30
What unit is used to measure apparent power?
What unit is used to measure apparent power?
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Volt-ampere (VA). VA measures the magnitude of AC power.
Volt-ampere (VA). VA measures the magnitude of AC power.
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Define the term 'active power' in AC circuits.
Define the term 'active power' in AC circuits.
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Real power. Active power performs actual work in circuits.
Real power. Active power performs actual work in circuits.
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State the expression for power factor in terms of real and apparent power.
State the expression for power factor in terms of real and apparent power.
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$\text{Power Factor} = \frac{P}{S}$. Power factor equals real power over apparent power.
$\text{Power Factor} = \frac{P}{S}$. Power factor equals real power over apparent power.
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State the relationship between power, energy, and time.
State the relationship between power, energy, and time.
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$P = \frac{E}{t}$. Power is energy divided by time.
$P = \frac{E}{t}$. Power is energy divided by time.
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Calculate the power if $V = 12 , V$ and $I = 0.5 , A$.
Calculate the power if $V = 12 , V$ and $I = 0.5 , A$.
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$P = 6 , W$. Using $P = VI = 12 \times 0.5 = 6$ W.
$P = 6 , W$. Using $P = VI = 12 \times 0.5 = 6$ W.
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State the formula for electric power in terms of resistance and current.
State the formula for electric power in terms of resistance and current.
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$P = I^2R$. Power equals current squared times resistance.
$P = I^2R$. Power equals current squared times resistance.
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What does a power factor of 1 signify in an AC circuit?
What does a power factor of 1 signify in an AC circuit?
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Purely resistive load. Unit power factor means no reactive components.
Purely resistive load. Unit power factor means no reactive components.
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State the formula for instantaneous power in terms of time.
State the formula for instantaneous power in terms of time.
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$p(t) = v(t) \cdot i(t)$. Instantaneous power is voltage times current.
$p(t) = v(t) \cdot i(t)$. Instantaneous power is voltage times current.
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What is the efficiency if $P_{\text{out}} = 90 , W$ and $P_{\text{in}} = 100 , W$?
What is the efficiency if $P_{\text{out}} = 90 , W$ and $P_{\text{in}} = 100 , W$?
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$\eta = 90%$. Efficiency = $\frac{90}{100} \times 100% = 90%$.
$\eta = 90%$. Efficiency = $\frac{90}{100} \times 100% = 90%$.
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What is the formula for electric power in terms of voltage and resistance?
What is the formula for electric power in terms of voltage and resistance?
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$P = \frac{V^2}{R}$. Power equals voltage squared divided by resistance.
$P = \frac{V^2}{R}$. Power equals voltage squared divided by resistance.
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What is the significance of reactive power in AC circuits?
What is the significance of reactive power in AC circuits?
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Non-working power. Reactive power doesn't perform useful work.
Non-working power. Reactive power doesn't perform useful work.
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Identify the unit of electric power in the International System of Units.
Identify the unit of electric power in the International System of Units.
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Watt (W). The SI unit for power is the watt.
Watt (W). The SI unit for power is the watt.
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How is reactive power denoted in an electrical circuit?
How is reactive power denoted in an electrical circuit?
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$Q$. $Q$ represents reactive power in circuits.
$Q$. $Q$ represents reactive power in circuits.
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What is the phase angle for a purely resistive circuit?
What is the phase angle for a purely resistive circuit?
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$0^\circ$. Resistive circuits have zero phase difference.
$0^\circ$. Resistive circuits have zero phase difference.
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What is the power output if $E = 500 , \text{J}$ and $t = 10 , \text{s}$?
What is the power output if $E = 500 , \text{J}$ and $t = 10 , \text{s}$?
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$P = 50 , W$. Using $P = \frac{E}{t} = \frac{500}{10} = 50$ W.
$P = 50 , W$. Using $P = \frac{E}{t} = \frac{500}{10} = 50$ W.
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Calculate the power if $V = 12 , V$ and $I = 0.5 , A$.
Calculate the power if $V = 12 , V$ and $I = 0.5 , A$.
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$P = 6 , W$. Using $P = VI = 12 \times 0.5 = 6$ W.
$P = 6 , W$. Using $P = VI = 12 \times 0.5 = 6$ W.
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Determine the power consumed by a $4 , \text{Ω}$ resistor with $3 , A$ current.
Determine the power consumed by a $4 , \text{Ω}$ resistor with $3 , A$ current.
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$P = 36 , W$. Using $P = I^2R = 3^2 \times 4 = 36$ W.
$P = 36 , W$. Using $P = I^2R = 3^2 \times 4 = 36$ W.
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What is the power dissipation if $V = 10 , V$ and $R = 5 , \text{Ω}$?
What is the power dissipation if $V = 10 , V$ and $R = 5 , \text{Ω}$?
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$P = 20 , W$. Using $P = \frac{V^2}{R} = \frac{10^2}{5} = 20$ W.
$P = 20 , W$. Using $P = \frac{V^2}{R} = \frac{10^2}{5} = 20$ W.
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What is the role of a transformer in power transmission?
What is the role of a transformer in power transmission?
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Adjusts voltage levels. Transformers step voltage up or down efficiently.
Adjusts voltage levels. Transformers step voltage up or down efficiently.
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Calculate the apparent power if $V = 220 , V$ and $I = 5 , A$.
Calculate the apparent power if $V = 220 , V$ and $I = 5 , A$.
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$S = 1100 , VA$. Using $S = VI = 220 \times 5 = 1100$ VA.
$S = 1100 , VA$. Using $S = VI = 220 \times 5 = 1100$ VA.
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Find the power factor if the power is $400 , W$, $I = 5 , A$, and $V = 100 , V$.
Find the power factor if the power is $400 , W$, $I = 5 , A$, and $V = 100 , V$.
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$\cos \phi = 0.8$. Power factor = $\frac{P}{VI} = \frac{400}{5 \times 100} = 0.8$.
$\cos \phi = 0.8$. Power factor = $\frac{P}{VI} = \frac{400}{5 \times 100} = 0.8$.
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What is the power loss in a transmission line given $I = 10 , A$ and $R = 2 , \text{Ω}$?
What is the power loss in a transmission line given $I = 10 , A$ and $R = 2 , \text{Ω}$?
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$P_{\text{loss}} = 200 , W$. Using $P_{\text{loss}} = I^2R = 10^2 \times 2 = 200$ W.
$P_{\text{loss}} = 200 , W$. Using $P_{\text{loss}} = I^2R = 10^2 \times 2 = 200$ W.
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Calculate the power if $I = 2 , A$ and $V = 5 , V$.
Calculate the power if $I = 2 , A$ and $V = 5 , V$.
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$P = 10 , W$. Using $P = IV = 2 \times 5 = 10$ W.
$P = 10 , W$. Using $P = IV = 2 \times 5 = 10$ W.
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What is the unit of reactive power?
What is the unit of reactive power?
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Volt-ampere reactive (VAR). VAR is the unit for reactive power.
Volt-ampere reactive (VAR). VAR is the unit for reactive power.
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State the relationship between power, energy, and time.
State the relationship between power, energy, and time.
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$P = \frac{E}{t}$. Power is energy divided by time.
$P = \frac{E}{t}$. Power is energy divided by time.
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State the expression for power factor in terms of real and apparent power.
State the expression for power factor in terms of real and apparent power.
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$\text{Power Factor} = \frac{P}{S}$. Power factor equals real power over apparent power.
$\text{Power Factor} = \frac{P}{S}$. Power factor equals real power over apparent power.
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Define apparent power in an AC circuit.
Define apparent power in an AC circuit.
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$S = VI$. Apparent power is the total power in AC circuits.
$S = VI$. Apparent power is the total power in AC circuits.
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State the formula for electric power in terms of resistance and current.
State the formula for electric power in terms of resistance and current.
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$P = I^2R$. Power equals current squared times resistance.
$P = I^2R$. Power equals current squared times resistance.
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Calculate power if $V = 120 , V$, $I = 3 , A$, and $\cos \phi = 0.9$.
Calculate power if $V = 120 , V$, $I = 3 , A$, and $\cos \phi = 0.9$.
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$P = 324 , W$. Using $P = VI\cos\phi = 120 \times 3 \times 0.9 = 324$ W.
$P = 324 , W$. Using $P = VI\cos\phi = 120 \times 3 \times 0.9 = 324$ W.
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How is reactive power denoted in an electrical circuit?
How is reactive power denoted in an electrical circuit?
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$Q$. $Q$ represents reactive power in circuits.
$Q$. $Q$ represents reactive power in circuits.
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