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An electric circuit is the physical pathway of a current. A simple electric circuit consists of the following:
• a source of electromotive force (e.m.f), e.g., a battery
• a load, e.g., a lamp
• wires connecting the various parts of the circuit
• additional components, e.g., switches
Voltage, current and resistance
Voltage, current and resistance
There are three basic electrical quantities in an electric circuit. They are Voltage , Current and Resistance.
What is voltage?
What is voltage?
Voltage (V) is the difference in electric potential between two points in an electric circuit. It is also known as the potential difference (p.d.) in electric charge in a circuit. A closely related term is “electromotive force” (e.m.f), which refers to the voltage of a source of energy, such as a battery. Voltage, or the potential difference between two points, is measured in volts (V). For example, we can say that the voltage across a lamp is 6 volts or 6 V.
What is current?
What is current?
Current (I ) is the flow of electric charge. Current is measured in amperes (A). For example, we can say that the current through a lamp is 2 amperes or 2 A.
What is resistance?
What is resistance?
Resistance (R) is the property of a material that opposes current. Resistance is measured in ohms (Ω). For example, we can say that the resistance of a lamp is 12 ohms or 12 Ω.
What is Ohm’s law?
What is Ohm’s law?
Ohm’s law states that the current (I ) through a conductor between two points is directly proportional to the voltage (V) across the two points, and inversely proportional to the resistance (R) between them. It can be expressed by the following equation: V = I X R
where R = resistance, V = voltage and I = current.
Solving for current, voltage, and resistance.
Solving for current, voltage, and resistance.
Calculating Ohm's Law
Calculating Ohm's Law
What is power?
What is power?
When a current passes through a load, such as a light bulb, the electrical energy is converted into other forms of energy such as heat energy and light energy. Power (P) is the rate at which the energy is converted.Power is measured in watts (W). For example, we can say that the power of a light bulb is 5 watts or 5 W. Typically, the greater the power rating of a light bulb, the brighter it is To calculate power in a circuit, the following formula is used: P = V X I
where P = power, V = voltage and I = current.
Series connections and parallel connections
Series connections and parallel connections
Series CONNECTIONS
Series CONNECTIONS
Resistors are in series when they are connected one after another (end to end). Since there is only one path for the current in the circuit, the current through each of the resistors is the same.
PARALLEL CONNECTIONS
PARALLEL CONNECTIONS
Resistors are in parallel when they are connected such that the circuit branches out at one point and joins up again at another point. Since there is more than one path for the current in the circuit, the current through each of the resistors is different. The current splits and then recombines at the points where the circuit branches out and joins up again. However, the potential difference across each resistor is the same.
PARALLEL RESISTORS CIRCUIT
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