PHEP 16

Question 1

What is capacitance?

Answer 1

That property which opposes any change in voltage * the ability of a caponet of a circuit to collect and store energy as a form of electrical charge

Question 2

What is Inductance?

Answer 2

That property that opposes any change in current

Question 3

What are the units of capacitance

Answer 3

Farads (f)

Question 4

What is capacitive reactance

Answer 4

Opposition offered by a capacitance to the flow of AC current through a capacitor and is expressed in Ohms XC=1/2πfC

Question 5

What will happen to the charging current in a capacitor if an alterating voltage is applied?

Answer 5

vary as voltage changes

Question 6

What is the purpose of insulation, or an insulator?

Answer 6

To prevent leakage or loss of current

Question 7

A dielectric is an insulator that is placed ____________.

Answer 7

between 2 conductors

Question 8

Define Capacitor

Answer 8

Any 2 conductors which are seperated by an insulator and designed to introduce capacitance within a circuit

Question 9

Describe dielectric strength

Answer 9

It’s a measure of the insulating property of the material

Question 10

Describe dielectric constant.

Answer 10

It’s a measure of an insulators effectiveness

Question 11

How do you measure dielectric strength?

Answer 11

It’s the voltage per centimeter that must be applied to rupture or breakdown an insulator.

Question 12

What is the constant used to determine a dielectric’s effectiveness?

Answer 12

The constant is air, which has a value of 1

Question 13

What are the three ways charging current can be increased in a capacitor?

Answer 13

-Voltage is increased -Size of the plates are increased -The plates are moved closer together

Question 14

The capacitance in farads is numerically equal to the quantity of electricity in _______.

Answer 14

Coulombs

Question 15

The intensity of the electrostatic field is proportional to?

Answer 15

the voltage between conductors

Question 16

The electrostatic field is propoertional to the _________ and the magnetic field is proportional to the __________ carried.

Answer 16

Voltage, & Current

Question 17

What is considered when constructing parallel-plate capacitors?

Answer 17

The amount of voltage they are to be subjected to.

Question 18

Capacitance is proportional to?

Answer 18

the cross-sectional area of the dielectric between the plates

Question 19

Total capacitance in a parallel circuit is?

Answer 19

Additive

Question 20

Total capacitance in a series circuit is?

Answer 20

Reciprocal of the reciprocal

Question 21

What are some capacitor applications?

Answer 21

-to smooth voltage ripples in DC circuits -minimize contact burning in inductive circuits - Supply energy to lightning impulse generators

Question 22

Capacity is a measure of the _________ of a capacitor to store electrons.

Answer 22

Ability

Question 23

The charging current, sincw it leads the voltage, tends to make the power factor of the system_______.

Answer 23

leading

Question 24

What determines Capacitance ( C)

Answer 24

-Type of dielectric -Area of plates -Distance between plates

Question 25

Capacitance is the electrical property which opposes any change is the? A) B) C) D)

Answer 25

Applied Voltage

Question 26

The property of an electrical non-conductor that permits the storeage of energy as a result of electrical displacement when opposite surfaces of the non-conductor are maintained at a difference of potential is called? A) B) C) D)

Answer 26

Capacitance

Question 27

A farad is most nearly associated with? A) B) C) D)

Answer 27

Capacitance

Question 28

Capacitance in a capacitor is NOT affected by the? A) B) C) D)

Answer 28

Resistance of the plates * what does affect capacitance -size of the conductors -size of the gap between them -the martial between them (the dielectric)

Question 29

One 20 microfarad capacitor and one 50 microfarad capacitor are connected in series. The total capacitance will be? A) B) C) D)

Answer 29

Less than the smallest capacitor 1/CT = 1/C1 + 1/C2 + 1/C3 1/CT = 1/20 + 1/50 1/CT = 7/100 CT = 100/7 CT = 14.28 microfarads

Question 30

It is desired to build up a capacitance of 6 micro farad. There are at hand three capacitors of 3, 4 and 5 mircofarad. What arrangement, using all three capacitors, will produce a capacitance nearest to 6 microfarads? A) B) C) D)

Answer 30

Series-Parallel series: 1/1/3+1/4+1/5 = 1.875 parallel: 3+4+5=12 series/parallel: 1/1/3+/15=1.875+4=5.875 (closest to 6 mircofarads)

Question 31

Whenever AC voltage is applied to the terminals of a capacitor, what happens with the max value of the current? A) B) C) D)

Answer 31

Leads the voltage peaks by 90 degrees (ICE)

Question 32

A long AC transmision line will generally have? A) B) C) D)

Answer 32

A leading power factor

Question 33

Capacitive reactance most nearly means? A) B) C) D)

Answer 33

A measure of opposition to alternating current (AC)

Question 34

In a DC circuit, the effects of capacitance are? A) B) C) D)

Answer 34

apparent when a change in the current magnitude occurs

Question 35

What is inductance? A) B) C) D)

Answer 35

A property that opposes any change in current

Question 36

What effects the capacitance of a capacitor? A) B) C) D)

Answer 36

-The area of the plates - The distance between the plates - the number of plates