Question 1

$E _ { L I N E } = \sqrt { E _R ^ { 2 } + E _X ^ { 2 } }$ The four dry cells are connected in series as shown. Find the total resistance. Carry the answer to three decimal places.

Accepted Answer

.167

Question 2

The total capacitance ( C ) is directly proportional to the product of the dielectric constant ( k ) and plate area ( A ) and inversely proportional to the thickness ( d ) of the dielectric.

Accepted Answer

A)    C=kdAC = \frac { k d } { A }C=Akd​ 
B)    C=kAdC = \frac { k A } { d }C=dkA​ 
C)    C=kdAC = \frac { k } { d A }C=dAk​ 
D)    C=dkAC = \frac { d } { k A }C=kAd​ B

Question 3

Find the number of watts in the armature of a generator having an internal resistance of 0.3 ohm and a voltage of 6 volts across the resistance. $$P = E ^ { 2 } / R$$

Accepted Answer

120

Question 4

$$E _ { L I N E } = \sqrt { E_ R ^ { 2 } + E_ X ^ { 2 } }$$ A lamp with a resistance (hot) of 50 ohms is connected across 120 volts. What current does the lamp receive?

Accepted Answer

The answer of \[E _ { L I N E...

Question 5

$E _ { L I N E } = \sqrt { E _R ^ { 2 } + E _X ^ { 2 } }$ A 60-volt electric time clock circuit with several clocks connected in parallel has a 2-wire line voltage drop of 12.5 volts when the circuit is closed. Using Ohm s law, find the total resistance of the 2-wire line if a current of 10 amps exists. Carry the answer to two decimal places.

Accepted Answer

The answer of \(E _ { L I N E...

Question 6

The resonant frequency ( $f _ { r }$ ) of a circuit containing both inductance ( L ) and capacitance ( C ) may be found by the reciprocal of two pi ( $2 \pi$ ) Hint:((The reciprocal is 1/$2 \pi$ )) multiplied by the square root of the product of the inductance and capacitance.

Accepted Answer

A)    fr=LC/2πf _ { r } = \sqrt { L C } / 2 \pifr​=LCc-2.7,0,-7.17,-2.7,-13.5,-8c-5.8,-5.3,-9.5,-10,-9.5,-14c0,-2,0.3,-3.3,1,-4c1.3,-2.7,23.83,-20.7,67.5,-54c44.2,-33.3,65.8,-50.3,66.5,-51c1.3,-1.3,3,-2,5,-2c4.7,0,8.7,3.3,12,10s173,378,173,378c0.7,0,35.3,-71,104,-213c68.7,-142,137.5,-285,206.5,-429c69,-144,104.5,-217.7,106.5,-221l0 -0c5.3,-9.3,12,-14,20,-14H400000v40H845.2724s-225.272,467,-225.272,467s-235,486,-235,486c-2.7,4.7,-9,7,-19,7c-6,0,-10,-1,-12,-3s-194,-422,-194,-422s-65,47,-65,47zM834 80h400000v40h-400000z"/>​/2π 
B)    fr=1/2πLCf _ { r } = 1 / 2 \pi \sqrt { L C }fr​=1/2πLCc-2.7,0,-7.17,-2.7,-13.5,-8c-5.8,-5.3,-9.5,-10,-9.5,-14c0,-2,0.3,-3.3,1,-4c1.3,-2.7,23.83,-20.7,67.5,-54c44.2,-33.3,65.8,-50.3,66.5,-51c1.3,-1.3,3,-2,5,-2c4.7,0,8.7,3.3,12,10s173,378,173,378c0.7,0,35.3,-71,104,-213c68.7,-142,137.5,-285,206.5,-429c69,-144,104.5,-217.7,106.5,-221l0 -0c5.3,-9.3,12,-14,20,-14H400000v40H845.2724s-225.272,467,-225.272,467s-235,486,-235,486c-2.7,4.7,-9,7,-19,7c-6,0,-10,-1,-12,-3s-194,-422,-194,-422s-65,47,-65,47zM834 80h400000v40h-400000z"/>​ 
C)    fr=L/2πLCf _ { r } = L / 2 \pi \sqrt { L C }fr​=L/2πLCc-2.7,0,-7.17,-2.7,-13.5,-8c-5.8,-5.3,-9.5,-10,-9.5,-14c0,-2,0.3,-3.3,1,-4c1.3,-2.7,23.83,-20.7,67.5,-54c44.2,-33.3,65.8,-50.3,66.5,-51c1.3,-1.3,3,-2,5,-2c4.7,0,8.7,3.3,12,10s173,378,173,378c0.7,0,35.3,-71,104,-213c68.7,-142,137.5,-285,206.5,-429c69,-144,104.5,-217.7,106.5,-221l0 -0c5.3,-9.3,12,-14,20,-14H400000v40H845.2724s-225.272,467,-225.272,467s-235,486,-235,486c-2.7,4.7,-9,7,-19,7c-6,0,-10,-1,-12,-3s-194,-422,-194,-422s-65,47,-65,47zM834 80h400000v40h-400000z"/>​ 
D)    fr=C/2πLCf _ { r } = C / 2 \pi \sqrt { L C }fr​=C/2πLCc-2.7,0,-7.17,-2.7,-13.5,-8c-5.8,-5.3,-9.5,-10,-9.5,-14c0,-2,0.3,-3.3,1,-4c1.3,-2.7,23.83,-20.7,67.5,-54c44.2,-33.3,65.8,-50.3,66.5,-51c1.3,-1.3,3,-2,5,-2c4.7,0,8.7,3.3,12,10s173,378,173,378c0.7,0,35.3,-71,104,-213c68.7,-142,137.5,-285,206.5,-429c69,-144,104.5,-217.7,106.5,-221l0 -0c5.3,-9.3,12,-14,20,-14H400000v40H845.2724s-225.272,467,-225.272,467s-235,486,-235,486c-2.7,4.7,-9,7,-19,7c-6,0,-10,-1,-12,-3s-194,-422,-194,-422s-65,47,-65,47zM834 80h400000v40h-400000z"/>​

Question 7

The internal resistance of five cells is 1.8 ohms each. The cells are connected as shown in the diagram to a 2-ohm resistance. What current, to the nearer hundredth, exists in the circuit? $E_ X$

Accepted Answer

The answer of The internal resistance of five cells is...

Question 8

The temperature of a motor rises to $E _ { C }$ C above room temperature. The room temperature is $E_ b$ C. What will a Fahrenheit thermometer read? Carry the answer to one decimal place. $E _ { a }$

Accepted Answer

The answer of The temperature of a motor rises to...

Question 9

What is the impedance ( Z ) of a coil with 84 ohms resistance ( R ) and 500 ohms reactance (X)? Round the answer to the nearer ohm. $$Z = \sqrt { R ^ { 2 } + X ^ { 2 } }$$

Accepted Answer

The answer of What is the impedance ( Z )...

Question 10

$$E _ { L I N E } = \sqrt { E_ R ^ { 2 } + E_ X ^ { 2 } }$$ What voltage is required to force a 4.5-amp current through an electric iron having a resistance of 25.5 ohms?

Accepted Answer

The answer of \[E _ { L I N E...

Question 11

Choose the correct formula to solve the problem. $$O P = V _ { 1 } ^ { 2 } + V _ { 2 } ^ { 2 } + 2 \left( V _ { 1 } \right) \left( V _ { 2 } \right) \cos \theta$$ $$I = E / R$$ $$E = I R$$ $$R = E / I$$ $$P = I ^ { 2 } R$$ $$I = P / E$$ $$E = P / I$$ $$R = E ^ { 2 } / p$$ $$P = E ^ { 2 } / R$$ $$I = \sqrt { P / R }$$ $$E = \sqrt { P R }$$ $$R = P / I _ { I ^ { 2 } }$$ How many watts will a motor use if the voltage is 240 volts and the motor is drawing 40 amps of current?

Accepted Answer

The answer of Choose the correct formula to solve the...

Question 12

$E _ { L I N E } = \sqrt { E _R ^ { 2 } + E _X ^ { 2 } }$ What is the current in amperes in a 3-phase circuit when the load is 67.5 horsepower, the efficiency is 90%, the voltage is 440 volts, and the circuit power factor is 0.80? Round the answer to the nearer hundredth. $$h p = \frac { \sqrt { 3 } ( E ) ( I ) ( E f f ) ( P F ) } { 746 }$$

Accepted Answer

The answer of \(E _ { L I N E...

Question 13

$E _ { L I N E } = \sqrt { E _R ^ { 2 } + E _X ^ { 2 } }$ A lamp requires a current of 0.94 amps when connected to a circuit with a voltage of 120 volts. Find the resistance in ohms of the lamp. Carry the answer to two decimal places.

Accepted Answer

The answer of \(E _ { L I N E...

Question 14

An electrical motor has a degree of efficiency ( Eff ) equal to the ratio of its useful output power ( $P _ { 0 }$ ) to the input power ( $p _ { 1 }$ ) required to operate it.

Accepted Answer

A)    Eff=P0P1E f f = \frac { P _ { 0 } } { P _ { 1 } }Eff=P1​P0​​ 
B)    Eff=P1P2E f f = \frac { P _ { 1 } } { P _ { 2 } }Eff=P2​P1​​ 
C)    Eff=P20P1E f f = \frac { P ^ { 2 } 0 } { P _ { 1 } }Eff=P1​P20​ 
D)    Eff=P1P0E f f = \frac { P _ { 1 } } { P _ { 0 } }Eff=P0​P1​​

Question 15

If a current of 4.5 amperes exists, what is the impedance of a circuit having a voltage of 110 volts across it? Express the answer to the nearer hundredth. $$\begin{aligned}
Z = \frac { E } { I } \quad \text { where } & Z = \text { impedance in ohms } \
& E = \text { voltage in volts } \
I & = \text { current in amperes }
\end{aligned}$$

Accepted Answer

The answer of If a current of 4.5 amperes exists,...

Question 16

$E _ { L I N E } = \sqrt { E _R ^ { 2 } + E _X ^ { 2 } }$ One 2-wire section of a 24-volt watchman clock signal system is operated through a 450-foot length of lead covered cable drawing 2 amps. The size of the conductor is number 18, and the diameter is 40.3 mils. What is the resistance of one conductor? Express the answer to the nearer whole number. $$\begin{array} { l l } 
C M = \frac { K L N } { d ^ { 2 } } & \
&\text { where }  N = \text { number of wires } \
& K = \text { constant } ( 10.8 ) \
& L = \text { length of one wire infeet } \
& R = \text { resistance in ohms } \
& d = \text { diameter in mils }
\end{array}$$

Accepted Answer

The answer of \(E _ { L I N E...

Question 17

A motor takes a current of 27.5 amperes per leaf on a 440-volt, three-phase circuit. The power factor is 0.80. What is the load in watts? Round the answer to the nearer whole watt. For a three-phase circuit: $I _ { S }$

Accepted Answer

The answer of A motor takes a current of 27.5...

Question 18

Choose the correct formula to solve the problem. $$a ^ { 2 } = b ^ { 2 } + c ^ { 2 }$$ $$E = I R$$ $$R = E / I$$ What voltage will be required to create a current of 5 milliamps through a wire-wound resister having a resistance of 750 ohms? Carry the answer to two decimal places.

Accepted Answer

The answer of Choose the correct formula to solve the...

Question 19

Solve the equation for the current ( I ) required by a motor when the horsepower, percent efficiency of the motor, and the voltage are known. $$\begin{aligned}
h p = \frac { ( E ) ( I ) ( E f f ) } { 746 } \quad \text { where } & l = \text { current in amperes } \
& E = \text { voltage in volts } \
& E f f = \text { efficiency of motor } \
& h p = \text { horsepower }
\end{aligned}$$

Accepted Answer

A)    I=746E×Eff×hpI = \frac { 746 } { E 	imes E f f 	imes h p }I=E×Eff×hp746​ 
B)    I=746(hp) E×EffI = \frac { 746 ( h p )  } { E 	imes E f f }I=E×Eff746(hp) ​ 
C)    I=(hp) 746E×EffI = \frac { ( h p )  } { 746 E 	imes E f f }I=746E×Eff(hp) ​ 
D)    I=E×Eff746(hp) I = \frac { E 	imes E f f } { 746 ( h p )  }I=746(hp) E×Eff​

Question 20

A circuit uses 216.2 watts and draws a current of 1.88 amps. Find the resistance. Express the answer to the nearer hundredth ohm. $$E = P / I$$ and $$R = E / I$$

Accepted Answer

The answer of A circuit uses 216.2 watts and draws...

Exam 8: Formulas

The total capacitance ( C ) is directly proportional to the product of the dielectric constant ( k ) and plate area ( A ) and inversely proportional to the thickness ( d ) of the dielectric.

Find the number of watts in the armature of a generator having an internal resistance of 0.3 ohm and a voltage of 6 volts across the resistance. $P = E ^ { 2 } / R$

$E _ { L I N E } = \sqrt { E_ R ^ { 2 } + E_ X ^ { 2 } }$ A lamp with a resistance (hot) of 50 ohms is connected across 120 volts. What current does the lamp receive?

The resonant frequency ( $f _ { r }$ ) of a circuit containing both inductance ( L ) and capacitance ( C ) may be found by the reciprocal of two pi ( $2 \pi$ ) Hint:((The reciprocal is 1/ $2 \pi$ ) ) multiplied by the square root of the product of the inductance and capacitance.

The internal resistance of five cells is 1.8 ohms each. The cells are connected as shown in the diagram to a 2-ohm resistance. What current, to the nearer hundredth, exists in the circuit? $E_ X$

The temperature of a motor rises to $E _ { C }$ C above room temperature. The room temperature is $E_ b$ C. What will a Fahrenheit thermometer read? Carry the answer to one decimal place. $E _ { a }$

What is the impedance ( Z ) of a coil with 84 ohms resistance ( R ) and 500 ohms reactance (X)? Round the answer to the nearer ohm. $Z = \sqrt { R ^ { 2 } + X ^ { 2 } }$

$E _ { L I N E } = \sqrt { E_ R ^ { 2 } + E_ X ^ { 2 } }$ What voltage is required to force a 4.5-amp current through an electric iron having a resistance of 25.5 ohms?

$E _ { L I N E } = \sqrt { E _R ^ { 2 } + E _X ^ { 2 } }$ A lamp requires a current of 0.94 amps when connected to a circuit with a voltage of 120 volts. Find the resistance in ohms of the lamp. Carry the answer to two decimal places.

An electrical motor has a degree of efficiency ( Eff ) equal to the ratio of its useful output power ( $P _ { 0 }$ ) to the input power ( $p _ { 1 }$ ) required to operate it.

A motor takes a current of 27.5 amperes per leaf on a 440-volt, three-phase circuit. The power factor is 0.80. What is the load in watts? Round the answer to the nearer whole watt. For a three-phase circuit: $I _ { S }$

Choose the correct formula to solve the problem. $a ^ { 2 } = b ^ { 2 } + c ^ { 2 }$ $E = I R$ $R = E / I$ What voltage will be required to create a current of 5 milliamps through a wire-wound resister having a resistance of 750 ohms? Carry the answer to two decimal places.

A circuit uses 216.2 watts and draws a current of 1.88 amps. Find the resistance. Express the answer to the nearer hundredth ohm. $E = P / I$ and $R = E / I$

Exam 8: Formulas

ELINE=ER2+EX2E _ { L I N E } = \sqrt { E _R ^ { 2 } + E _X ^ { 2 } }ELINE​=ER2​+EX2​​ The four dry cells are connected in series as shown. Find the total resistance. Carry the answer to three decimal places.

The total capacitance ( C ) is directly proportional to the product of the dielectric constant ( k ) and plate area ( A ) and inversely proportional to the thickness ( d ) of the dielectric.

Find the number of watts in the armature of a generator having an internal resistance of 0.3 ohm and a voltage of 6 volts across the resistance. P=E2/RP = E ^ { 2 } / RP=E2/R

ELINE=ER2+EX2E _ { L I N E } = \sqrt { E_ R ^ { 2 } + E_ X ^ { 2 } }ELINE​=ER2​+EX2​​ A lamp with a resistance (hot) of 50 ohms is connected across 120 volts. What current does the lamp receive?

The resonant frequency ( frf _ { r }fr​ ) of a circuit containing both inductance ( L ) and capacitance ( C ) may be found by the reciprocal of two pi ( 2π2 \pi2π ) Hint:((The reciprocal is 1/ 2π2 \pi2π ) ) multiplied by the square root of the product of the inductance and capacitance.

The internal resistance of five cells is 1.8 ohms each. The cells are connected as shown in the diagram to a 2-ohm resistance. What current, to the nearer hundredth, exists in the circuit? EXE_ XEX​

The temperature of a motor rises to ECE _ { C }EC​ C above room temperature. The room temperature is EbE_ bEb​ C. What will a Fahrenheit thermometer read? Carry the answer to one decimal place. EaE _ { a }Ea​

What is the impedance ( Z ) of a coil with 84 ohms resistance ( R ) and 500 ohms reactance (X)? Round the answer to the nearer ohm. Z=R2+X2Z = \sqrt { R ^ { 2 } + X ^ { 2 } }Z=R2+X2​

ELINE=ER2+EX2E _ { L I N E } = \sqrt { E_ R ^ { 2 } + E_ X ^ { 2 } }ELINE​=ER2​+EX2​​ What voltage is required to force a 4.5-amp current through an electric iron having a resistance of 25.5 ohms?

ELINE=ER2+EX2E _ { L I N E } = \sqrt { E _R ^ { 2 } + E _X ^ { 2 } }ELINE​=ER2​+EX2​​ A lamp requires a current of 0.94 amps when connected to a circuit with a voltage of 120 volts. Find the resistance in ohms of the lamp. Carry the answer to two decimal places.

An electrical motor has a degree of efficiency ( Eff ) equal to the ratio of its useful output power ( P0P _ { 0 }P0​ ) to the input power ( p1p _ { 1 }p1​ ) required to operate it.

A motor takes a current of 27.5 amperes per leaf on a 440-volt, three-phase circuit. The power factor is 0.80. What is the load in watts? Round the answer to the nearer whole watt. For a three-phase circuit: ISI _ { S }IS​

A circuit uses 216.2 watts and draws a current of 1.88 amps. Find the resistance. Express the answer to the nearer hundredth ohm. E=P/IE = P / IE=P/I and R=E/IR = E / IR=E/I

Find the number of watts in the armature of a generator having an internal resistance of 0.3 ohm and a voltage of 6 volts across the resistance. $P = E ^ { 2 } / R$

$E _ { L I N E } = \sqrt { E_ R ^ { 2 } + E_ X ^ { 2 } }$ A lamp with a resistance (hot) of 50 ohms is connected across 120 volts. What current does the lamp receive?

The resonant frequency ( $f _ { r }$ ) of a circuit containing both inductance ( L ) and capacitance ( C ) may be found by the reciprocal of two pi ( $2 \pi$ ) Hint:((The reciprocal is 1/ $2 \pi$ ) ) multiplied by the square root of the product of the inductance and capacitance.

The internal resistance of five cells is 1.8 ohms each. The cells are connected as shown in the diagram to a 2-ohm resistance. What current, to the nearer hundredth, exists in the circuit? $E_ X$

The temperature of a motor rises to $E _ { C }$ C above room temperature. The room temperature is $E_ b$ C. What will a Fahrenheit thermometer read? Carry the answer to one decimal place. $E _ { a }$

What is the impedance ( Z ) of a coil with 84 ohms resistance ( R ) and 500 ohms reactance (X)? Round the answer to the nearer ohm. $Z = \sqrt { R ^ { 2 } + X ^ { 2 } }$

$E _ { L I N E } = \sqrt { E_ R ^ { 2 } + E_ X ^ { 2 } }$ What voltage is required to force a 4.5-amp current through an electric iron having a resistance of 25.5 ohms?

$E _ { L I N E } = \sqrt { E _R ^ { 2 } + E _X ^ { 2 } }$ A lamp requires a current of 0.94 amps when connected to a circuit with a voltage of 120 volts. Find the resistance in ohms of the lamp. Carry the answer to two decimal places.

An electrical motor has a degree of efficiency ( Eff ) equal to the ratio of its useful output power ( $P _ { 0 }$ ) to the input power ( $p _ { 1 }$ ) required to operate it.

A motor takes a current of 27.5 amperes per leaf on a 440-volt, three-phase circuit. The power factor is 0.80. What is the load in watts? Round the answer to the nearer whole watt. For a three-phase circuit: $I _ { S }$

A circuit uses 216.2 watts and draws a current of 1.88 amps. Find the resistance. Express the answer to the nearer hundredth ohm. $E = P / I$ and $R = E / I$