Ohm's Law and resistance
All A material which allows charge to move easily through it. show some opposition to electrical Moving electric charges, eg electrons moving through a metal wire.. This opposition to current is called The opposition in an electrical component to the movement of electrical charge through it. Resistance is measured in ohms.. There are several factors that affect the resistance of a conductor;
- material, eg copper, has lower resistance than steel
- length - longer wires have greater resistance
- thickness - smaller diameter wires have greater resistance
- temperature - heating a wire increases its resistance
The two main ways of increasing the current in an electrical circuit are by increasing the voltage or by decreasing the resistance.
Changing the voltage
If you increase the voltage across a component, there will be more current in the Parts of an electrical circuit, eg resistors, lamps, motors etc.. Too high a voltage and the lamp will break.
Changing the resistance
If you increase the number of lamps in a A circuit where one component follows directly from another, eg three bulbs in a row with no junctions are said to be connected in series.A closed loop through which current moves - from a power source, through a series of components, and back into the power source., there will be less current. The lamps resist current, so if you put more lamps into the circuit, there is more resistance.
You could increase or decrease the resistance in a circuit by using a A resistor where the value of the resistance can be changed..
The quantities voltage, current and resistance are linked by the A relationship tells us how two or more variables work together, eg the relationship between resistance, voltage and current is: resistance = voltage ÷ current.:
\(voltage = current \times resistance\)
This relationship is called The unit of electrical resistance, whose symbol is Ω. Law. We usually write Ohm's Law as;
\(V = IR\)
The symbol for resistance is R, it is measured in ohms \((\Omega )\).
The symbol for The potential difference across a cell, electrical supply or electrical component. It is measured in volts (V). is V, it is measured in volts \((V)\).
The symbol for current is I, it is measured in amperes \((A)\).
Make sure that if there is more than one voltage or current in a problem, you use the voltage across the An electrical component that restricts the flow of electrical charge. Fixed-value resistors do not change their resistance, but with variable resistors it is possible to vary the resistance. and the current through it, not just any values that you see in the question.
