Deck 3: Electrical Power and Energy

Question 1

What is one possible downside of oversizing a motor?

A) wasted power
B) excessive motor heating
C) insulation breakdown
D) tripping overcurrent devices

Answer 1

A

Question 2

Efficiency is the ratio of the unused power output to the total power input.

Answer 2

False

Question 3

When using a PIRE wheel, you should select a formula in the quadrant of ____.

A) Power
B) the unknown variable
C) Resistance
D) a known variable

Answer 3

B

Question 4

Electrical power, in watts, can be expressed as the product of current, in amperes and electrical pressure, in volts.

Question 5

The ____ of a motor is the amount of torque developed at the instant the motor is energized.

A) starting torque
B) opening torque
C) initial torque
D) rated load torque

Question 6

Which of these is an example of a driven machine?

A) steam turbine
B) gasoline engine
C) electric motor
D) elevator

Question 7

How much power is dissipated by an electric oven if 30 A flows through a resistance of 10 ohms?

A) 9.2 W
B) 7.52 kW
C) 9 kW
D) 9000 kW

Question 8

Energy loss occurs whenever energy is destroyed or consumed.

Question 9

A(n) ____connected in series with a motor will both limit and control the starting current.

A) alternator
B) torque converter
C) rheostat
D) thermostat

Question 10

Power is a measurement of the rate of doing work.

Question 11

Heat energy can be measured in ____.

A) degrees Celsius
B) British thermal units
C) ohms
D) watts

Question 12

With direct drive, the driving machine and the driven machine may be mounted on the same shaft, or a(n) ____ may be used.

A) reducer
B) pulley
C) shaft coupling
D) gear shaft

Question 13

Work equals force multiplied by ____.

A) current
B) power
C) energy
D) distance

Question 14

With which type of drive will the driven gear rotate in the opposite direction from the driving gear?

A) chain drive
B) two-gear drive
C) three-gear drive
D) direct drive

Question 15

Electrical energy is the product of power and time.