Principles Of Electrical Science Flashcards
What are the 2 main parts of an atom?
The nucleus and the electron cloud
Which part of an atom has a negative charge?
The electron
Which part of an atom has a positive charge?
Proton
In electron current theory, in which direction do the electrons flow?
From the negative terminal through the conductor to the positive terminal
What is the charge state of an atom with an extra electron?
Negatively charged
What is conventional current flow?
The flow of electrons from negative to positive
State three effects of an electric current
Thermal effect
Chemical effect
Magnetic effect
What is the smallest atom?
Hydrogen
What is the heaviest atom?
Uranium
What is the unit of electric current?
Ampere
True or False: Voltage is the measure of electric potential difference.
True
Fill in the blank: The formula for Ohm’s Law is ________.
V = IR
What does the symbol ‘R’ represent in electrical equations?
Resistance
What is the SI unit of resistance?
Ohm
Which law states that the current through a conductor between two points is directly proportional to the voltage across the two points?
Ohm’s Law
What is the relationship between power (P), voltage (V), and current (I)?
P = VI
True or False: Direct current (DC) flows in one direction only.
True
What type of current alternates direction?
Alternating current (AC)
What is the unit of electrical power?
Watt
Multiple Choice: Which of the following is a conductor? A) Rubber B) Copper C) Wood
B) Copper
What is capacitance?
The ability of a system to store an electric charge.
What is the unit of capacitance?
Farad
Fill in the blank: The energy stored in a capacitor can be calculated using the formula ________.
E = 1/2 CV^2
What does an inductor do in a circuit?
Stores energy in a magnetic field.
True or False: Resistance is independent of temperature.
False
What is Kirchhoff’s First Law?
The sum of currents entering a junction must equal the sum of currents leaving the junction.
What is the formula for calculating total resistance in series circuits?
R_total = R1 + R2 + R3 + …
What is the formula for calculating total resistance in parallel circuits?
1/R1 + 1/R2 + 1/R3 so on
What is the main purpose of a fuse in an electrical circuit?
To protect the circuit from overcurrent.
Fill in the blank: The relationship between frequency (f) and period (T) is ________.
f = 1/T
What is the principle of electromagnetic induction?
A changing magnetic field can induce an electric current.
True or False: A transformer can increase or decrease voltage levels.
True
What type of circuit provides multiple paths for current to flow?
Parallel circuit
What is the primary function of a resistor in a circuit?
To limit the electric current.
Multiple Choice: Which of the following is a semiconductor? A) Silicon B) Copper C) Gold
A) Silicon
What is the equation for resistance in a circuit?
Volts / amp
What is the SI unit of temperature?
Kelvin
What would a 2.5sq/mm twin and earth cable would usually be used for?
A domestic ring circuit
What is the ‘constant’ for RMS values?
0.707
What is the name of the insulating medium used in a MI cable?
Magnesium oxide
What is the main purpose of ‘equipotential bonding’ ?
To maintain all exposed metal work at the same potential
What is the formula for work done?
Force x distance
What is the formula for resistance in a circuit?
Volts / ampere
If current in a circuit remained constant and voltage increased the resistance of the circuit would….
Increase
