Week 1 Flashcards
What are the 4 basic elements of an electrical circuit?
source
load
switch
conductors
What is a source in an electric circuit?
a source that delivers electricity, eg. generators, batteries, alternators
What is a load in an electric circuit?
A load that consumes the supplied electricity, e.g., light bulbs, motors, relays etc.
What is a switch in an electric circuit?
A switch that controls the “on” and “off” of the load
What is a conductors in an electric circuit?
Connecting conductors
What are 4 circuit symbol sources in an independent source?
dc voltage source
ac voltage source
battery
current source
What are 2 circuit symbol sources in an dependent source?
Dependent voltage source
dependent current source
What is a current?
Electric current (i) is defined as the rate at which charge (q) flows through a surface (for example, the cross section of a wire)
Is current measured through or across an element?
Current is always measured through an element
What is a voltage?
Voltage (v), also called electromotive force, is the potential difference in charge between two points in an electrical field
Is voltage measured through or across an element?
Voltage is always measured across an element
What is resistance?
The resistance (R) of a material is the property to resist the flow of charges when an external electric field is applied
What is resistance of a material depend on?
Resistance of a material depends on its length (l), cross sectional area (A)
and the resistivity of the material (p)
What is Ohm’s law?
At a given temperature, the current through a conductor (I) between two points is directly proportional to the potential difference (V) between those two points. The proportionality constant depends on the resistance (R) between the two points
What is the direction which conventional current flow go?
Clockwise
Conventional current flow direction is same as the direction of positive charges
What is the direction which electron flow go?
Anticlockwise
What is electrical power?
Rate of energy absorbed or produced within the circuit
What is electrical energy?
Electrical power within a circuit consumed over a period of time
What is a series circuit?
Any electric circuit having all elements joined in a sequence such that the same current flows through them all. Voltage across the circuit is the sum of the voltages across each element
What is a parallel circuit?
In a parallel circuit both terminals of an element are respectively connected to each terminal of the other element or elements. Voltage across each element is the same and the total current is the sum of the currents through each element
What is kirchoff’s current law?
The sum of the currents entering a junction of a network is equal to the sum of the currents leaving the same junction
What is the sum of voltages difference across a closed loop network equal to?
∑ V = 0 for a closed loop
What direction, voltage polarity is a closed loop?
In this circuit, the current is assumed to be in the clockwise direction. Then the voltage polarities across each resistor will be as shown. The current entering end of a resistor will have a positive (+) polarity and the leaving end will have a negative (-) polarity
What are ammeters connected by, series or parallel?
Ammeters are always connected in series so that the current to be measured should go through it. They have a negligible internal resistance, Hence the magnitude of the current will not change due to the insertion of an ammeter when it is connected in series
What is the voltage and resistance and what will happen to the current in an open circuit?
- No current will go through the open circuit between a and b
- Resistance across a and b is very high (infinity)
- Voltage across a and b depends on the other elements in the circuit and it will not be zero
What is the voltage and resistance and what will happen to the current in an short circuit?
- Voltage across a and b is zero, Vab = 0
- There will be a current going through the short circuit between a
and b
- Resistance across a and b is zero
