Electricity Review
Topics covered
• Characteristics of Dynamic Electricity– Intensity– Resistance– Potential Difference– Energy– Electrical Power– Work
• Circuit designs
Characteristics
1. IntensityA. Definition
• The number of charges that flow past a given point in 1 second
Characteristics
B. Units:– The Current Intensity is measured in Amperes (A)
C. Formula:– I = q/∆t
• Where I = Intensity (A)
q = Charges (C)
∆t = variation in time (sec)
D. In a circuit:
A
Characteristics
2. ResistanceA. Definition
• The ability to slow down the electrons. The ability of a material to hinder the flow of the electric curent.
Characteristics
B. Units:– The Resistance is measured in Ohms (Ω)
C. Formula:– V = R I
• Where V = Potential Difference (V)R = Resistance (Ω) I = Intensity (A)
D. In a circuit:
Characteristics
E. Factors affecting resistance– Nature of the substance
• Better Conductor = Less resistance
– Length• The shorter, the less resistance
– Diameter• The fatter, the less resistance
– Temperature• The colder, the less resistance
Characteristics
3. Potential DifferenceA. Definition
• The amount of energy transferred between two points in an electrical circuit.
V
Characteristics
B. Units:– The Potential Difference is measured in Volts (V)
C. Formula:– V = E/q
• Where V = Potential Difference (V)
E = Electric Energy (J)
q = Charge (C)
D. In a circuit:
V
Characteristics
4. Electrical PowerA. Definition
• The amount of work an electrical device can perform per second or how much energy it can transform in a period of time.
Characteristics
B. Units:– The Electrical Power is measured in Watts (W)
C. Formula:– Pe = W/∆t
• Where Pe = Electrical Power (W) W = Work (J) ∆t = Time Interval (sec)
– Pe = V I• Where Pe = Electrical Power (W)
V = Potential Difference (V) I = Intensity (A)
Characteristics
C. Formula (Continued)– E = Pe∆t
• Where E = Electrical Energy (J or kWh)
Pe = Electrical Power (Pe)
∆t = Time Interval (sec or hours)
Electrical Circuits
Electrical Circuits
• Types of electrical circuitsA. Series circuit
• Definition:– Circuit that contains only one branch or path for the
electrons to follow.
• Characteristics– If one element is defective, the electricity does not flow– The intensity is the same all around the circuit– The resistance adds up
Electrical Circuits
B. Parallel circuit• Definition
– Circuit that contains at least one branch or paths for the electrons to follow.
• Characteristics– If an element is defective, the elements on that
particular branch will stop working only– Resistance is shared (so resistance is lower)– Current intensity adds up
Electrical oddities
• A switch must be closed in order to allow the energy to flow
• A light will only light up when the electrons complete a full circuit (one side of the power source to another)
Top Related