Download (Output power / Input power) x 100 Power in (Watts) = Volts x Amps

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Principles of Engineering Quiz Review – Unit 1.2 – Energy Sources - KEY

The unit of electrical current is the amp.

Fuels that use animal or food products/by-products are known as biofuels.

The energy of motion or moving objects is called kinetic energy.

A circuit in which all parts are connected end to end forming a single path for current flow series circuit.

An energy resource that cannot be replaced once used. Non-renewable.

An energy source that will never run out. Inexhaustible.

The mathematical relationship between electrical resistance, voltage, & current is known as Ohm’s Law.

The energy that a piece of matter has because of its position or nature or because of the arrangement of
parts. Potential energy.

A term used to describe the energy loss in a system. Entropy.

The amount of charge flowing in a circuit in a period of time is known as current.

The unit of electrical resistance is the ohm.

An object raised a distance above the floor or ground has what form of energy? Grav. Potential energy.

Energy derived from the heat that exists in the ground is known as Geothermal.

An energy resource that can be replaced when needed. Renewable.

Materials that do NOT allow current to flow through them easily are considered insulators.

The rate at which work is performed or energy is expended is known as power.

The force-like quantity in electrical systems (potential difference) that pushes or moves charge voltage.

A result (the product) of a force moving an object a certain distance: work.

An electrical circuit in which there are multiple loads and multiple paths for current to flow: parallel.

The ratio of input work/power to output work/power is known as efficiency.
Are these energy sources renewable, non-renewable or inexhaustible?
Oil N
Solar I
Geothermal I
Hydroelectric I
Natural Gas N
Tidal I
Biofuels R
Wind I
Uranium N
Ethanol R
Coal N
Hydrogen I
Formulas & Conversions:
Efficiency % = (Output power / Input power) x 100
Power in (Watts) = Volts x Amps
Power = Work / Time
101.97 g = 1 Newton; 1 gm = .0098 Newton; 1 kg = 9.8 Newton;
Work (J) = Force (N) x Distance (m)
1 N-m = 1 joule; 1 meter = 100 cm
Part 2 – Work & Power Calculations:
An 120 volt electric motor that draws 5 amps of current operates a winch that lifts a 100 kg. a distance
of 300 cm. in 5 seconds. Find work done by the winch, input power, output power and efficiency of this
system.
How much weight was lifted?
980 Newtons
How many meters did the weight travel?
3 Meters
How much output work (in joules) was done by the system?
2,940 Joules
What is the output power of the system (in watts).
588 Watts
What is the input power of the system (in watts)
600 Watts
What is the system efficiency?
98%
Part 3 – Electrical Circuits & Ohm’s Law – Include Proper Units with ALL Answers:
A circuit is set up with 12V and a 150 Ohm resistor. Find the current in this system.
.08 amps (80 mA)
A circuit is set up with 9V and has a 20mA current running through the system. Find resistance.
450 ohms
A circuit has a 1 K-Ohm resistor and has a .05A current running through it. Find voltage.
50 volts
42. Using the laws of circuit theory, solve for RT, IT, VR1,
VR2, & VR3. Be sure to put your answer in proper
engineering notation and use the correct units.
=
390 Ω
43. Using the laws of circuit theory, solve for RT, IT, IR1, IR2,
& IR3. Be sure to put your answer in proper engineering
notation and use the correct units.
1.5 KΩ
12 V
3.2 KΩ
7.4 KΩ
24 V
2.4 KΩ
470 Ω
RT = 2,360 ohms IT = .0051 A (or 5.1 mA)
VR1 = 1.95 V
VR2 = 7.5 V
VR3 = 2.35 V
Ohm’s Law Formulas: V = I x R
Resistance in Series: RT = R1 + R2 + R3
RT = 1,162 ohms IT = .0206 A (or 20.6 mA)
IR1 = .0032 A IR2 = .0075 A IR3 = .01 A
or 3.2 mA
R=V/I
or 7.5 mA
or 10 mA
I=V/R
Resistance in Parallel: RT =
1
1/R1 + 1/R2 + 1/R3