E Ch 2

Question 1

What 3 elements are required for a circuit?

Answer 1

Power source, conductors, and load

Question 2

A “load” is a device that:

Answer 2

Uses electrical energy

Question 3

What basic function do all switches perform?

Answer 3

Open and close

Question 4

The polarity of source voltage determines in which direction current flow is in. The amount of voltages determines what?

Answer 4

How much current will flow

Question 5

Name 2 factors that determine how much current flows in a DC circuit:

Answer 5

Voltage and resistance

Question 6

The ease with which a metal allows current to flow is called?

Answer 6

Conductance

Question 7

What is the best conductor?

Answer 7

Silver

Question 8

Resistance depends on what?

Answer 8

Number of free electrons (?)

Question 9

How can you create any resistance you want?

Answer 9

By choosing the proper metal for the conductor and making it a certain length and cross-sectional area

Question 10

What is the unit of resistance?

Answer 10

Ohms

Question 11

The resistance of a load is generally what compared to the resistance of the circuit wiring?

Answer 11

Much greater

Question 12

Every power source has what?

Answer 12

Internal resistance

Question 13

Name one or two methods of decreasing large currents in a circuit with fixed voltage?

Answer 13

Add resistance to the circuit

Question 14

One material used to make a resistor?

Answer 14

Carbon

Question 15

Resistors have an indication value. Actual value may vary. What is that called?

Answer 15

Resistor tolerance

Question 16

All resistors are designed for a max current value. What is the rating called?

Answer 16

Wattage rating

Question 17

3 advantages of a composition resistor?

Answer 17

Small, rugged, and low cost

Question 18

A property of resistor maintaining a small tolerance under operating conditions?

Answer 18

Stability of resistor

Question 19

When all 3 terminals of a variable resistor are connected, what is it called?

Answer 19

Potentiometer

Question 20

When only the center terminal and one other of a variable resistor are connected, what is it called?

Answer 20

Rheostat

Question 21

In ohms law, if you raise voltage, the current will?

Answer 21

Go up

Question 22

I’m ohms law, if you lower resistance…?

Answer 22

Current will go up

Question 23

It’s good practice to think of Ohm’s law in terms of:

Answer 23

Knows and unknowns

Question 24

What is power?

Answer 24

The rate of doing work

Question 25

One watt equals?

Answer 25

The power used when 1 amp of current flows through a potential difference of 1 volt.

Question 26

Power rating of working equipment (such as motors) are not based on I^2•R losses, what is it?

Answer 26

They are based mostly on the power they can use to do mechanical work

Question 27

Total power used by consumer and sold by power companies is in what unit?

Answer 27

Kilo-watt hours

Question 28

1000V= ?kV

Answer 28

1kV

Question 29

1 million volts = ? MegaVolts

Answer 29

1 MegaVolt

Question 30

Current is __________ in series circuits.

Answer 30

Constant

Question 31

When the negative terminal of a battery is connected to the positive terminal of another battery, the batteries are connected in ________?

Answer 31

Series

Question 32

When power sources are connected in series, total voltage is _________?

Answer 32

The sum of individual voltages

Question 33

If power sources are connected so their polarities are not in the same direction…..

Answer 33

They will oppose each other

Question 34

In series, total voltage drop is equal to _________

Answer 34

Source voltage

Question 35

In a DC series circuit, it’s polarity is from:

Answer 35

Negative battery terminal, through the circuit, to the positive terminal

Question 36

A short circuit is when current flows:

Answer 36

Without going through a load

Question 37

The electromagnetic circuit breaker works on the principle of:

Answer 37

Magnetism, to open the circuit

Question 38

In a parallel circuit, current _________?

Answer 38

Divides and follows different paths

Question 39

In a parallel circuit, total current _______?

Answer 39

Is the sum of branch currents

Question 40

The reciprocal method is used for what in a circuit?

Answer 40

Total resistance

Question 41

Power consumed in a circuit is _______?

Answer 41

Additive

Question 42

Most resistor failures are a result of ____________?

Answer 42

Heat generated in resistor by current flow

Question 43

A good conductor has __________ resistance, and good insulators have _________ resistance.

Answer 43

Low; high

Question 44

What determines the resistance of a conductor?

Answer 44

Cross-sectional area and length

Question 45

EMF is measure in ________?

Answer 45

Volts

Question 46

Kirchhoff’s first law is?

Answer 46

Sum of voltage drops in a closed loop = Sum of EMFs in loop