resistance

• resistance happens in electrical circuits when a component resists the flow of current
• most conductors will resist the flow of current in a cuicuit
• there is more resistance in a wire if:

  the wire is thinner

  the wire is longet
• insulators will have a very high resistance so current will not flow through them
• resistance = potential difference (V) divided by current (A)
• a resistor is said to follow ohms law if:

  the current that flows through it is directly proportional to the potential difference
• a directly proportional relationship when you draw it on a graph is a straight line through the origin
• tasers are non lethal because they have a high voltage and low current
• V=IR (Voltage= Current x Resistance)
• • Resistance can be calculated using the equation: Resistance = potential difference ÷ current
• resistance happens because negatively charged electrons collide with positive ions, transferring energy. the more collisions the more the resistance.
• It can be useful to add resistance to a circuit. For example, increasing resistance can make a motor spin more slowly, or make a lamp light less bright. A component called a resistor can be added in series to a circuit to increase the total resistance.
• Potential difference (p.d.) is the amount of energy transferred by each unit of charge passing between two points of a circuit