Fourth Period Math Applications

Question 1

What is Ohms Law?

Answer 1

I = E/R

Question 2

How do you add resistance in a series resistive circuit?

Answer 2

RT = R1 + R2 + R3

Question 3

What is the fomula for Capacitive Reactance?

Answer 3

Xc = (1 / 2 π fC)

Question 4

What is the formula for Inductive Reactance?

Answer 4

2 π fL

Question 5

What is a phase angle?

Answer 5

The phase angle is the number of degrees by which the current through the component leads or lags the voltage across the component.

Question 6

What is a power factor?

Answer 6

The power factor is equal to the cosine of the angle of the impedance triangle and usually expressed in decimal form.

Question 7

What is true power?

Answer 7

True power is sometimes called real power or active power. This is expressed by the letter “P”. It is the result of an in-phase component (R). It is measured in WATTS.

Question 8

What is reactive power?

Answer 8

Reactive power is the result of an out of phase component (X). It is expressed by the letter “Q”. Reactive power is measured in vars.

Question 9

What is apparent power?

Answer 9

Apparent power is the total power of a circuit containing in phase and out of phase components. This is found using Z. Apparent power is expressed by the letter S and measured in VA.

Question 10

In a series circuit with only one load which is purely inductive, does current lead or lag voltage? By how many degrees?

Answer 10

Current lags an inductive voltage drop by 90 degrees.

Question 11

In a series circuit with only one load which is purely capacitive, does current lead or lag voltage? By how many degrees?

Answer 11

Current leads a capacitive voltage drop by 90 degrees.

Question 12

In a parallel RLC circuit, how do you find total current?

Answer 12

In a parallel RLC circuit, total current is determined by the phasor sum of the currents that flow through each branch of the circuit. The current for each branch is found using an impedance diagram for that branch.

Question 13

In a Wye-connected circuit, how far apart are the line and phase voltages?

Answer 13

120 degrees

Question 14

In a Wye-Connected circuit, explain the relationship between line and phase voltages.

Answer 14

Line voltages are (ROOT3 x phase voltages) and lead phase voltages by 30 degrees.

Line current = Phase current

Question 15

If the line voltage for a three-phase wye system ins 4160V, what is the phase voltage?

Answer 15

2401.777V

Question 16

A

Answer 16

A

Question 17

Can you measure phase voltage in a three wire Delta system?

Answer 17

No, only line voltage can be measured.

Question 18

How far apart are line voltages in a 3 wire Delta system?

Answer 18

120 degrees

Question 19

In balanced delta circuits, how do line currents compare to phase currents?

Answer 19

Line currents are (ROOT3 x phase current)

Question 20

If the line voltage of a three-phase delta system is 600V, what is the phase voltage?

Answer 20

600V

Question 21

If the line current of a three-phase delta system that has a balanced load is 75A, what is the phase current?

Answer 21

43.301A