Question

Differentiate between:

(1) Resistances in series and parallel.

(2) Conductors and insulators.

(3) Resistance and resistivity.

(4) High resistance and low resistance.

Answer 1

(1) Difference between resistance in series and parallel:

		Resistance in Series		Resistance in Parallel
1.		Voltage (potential) drop across each resistor is different if their values of resistance are different.		Potential difference across the entire resistance remains the same whatever their values.
2.		Current through all the resistances remains the same whatever their values.		Current flow through each resistor is different if their values are different.
3.		Equivalent resistance in a series circuit is given by: RT = R1 + R2 + …+ Rn		Equivalent resistance in a parallel circuit is given by:
4.		Net resistance is greater than individual resistances.		Net resistance is less than individual resistances.
5.		Such combination is used to increase the net resistance in a circuit.		Such combination is used to reduce the net resistance in a circuit.

(2) Difference between conductors and insulators:

		Conductors		Insulators
1.		A conductor allows flow of electric current through it when a potential difference is applied across its ends.		An insulator does not conduct electricity unless very high potential difference is applied across its ends.
2.		A good conductor of electricity is generally a good conductor of heat.		Insulators do not conduct heat.
3.		Conductors have free electrons on their surfaces.		Insulators have bounded electrons on their surfaces.
4.		Example of conductors: Silver (Ag), Copper (Cu), Aluminium (Al) etc.		Examples of insulators: Ebonite, Sulphur, Poly-vinyl Chloride etc.
5.		They have low resistance.		They have high resistance.

(3) Difference between resistivity and resistance:

		Resistivity		Resistance
1.		Resistivity is the measure of a material’s ability to oppose the flow of current.		Resistance is a measure of the opposition that a wire offers to the flow of electric current.
2.		The resistivity depends upon the nature of material only.		The resistance of a material depends on length, thickness, nature of material and temperature of the conductor.
3.		Unit of resistivity is Ohm meter (Ω m).		Unit of resistance is Ohm (Ω).

(4) Difference between high resistance and low resistance:

		High resistance		Low resistance
1.		A substance has a high resistance when it does not readily allow the flow of an electric current through it.		A substance has a low resistance when it readily allows the flow of an electric current through it.
2.		Most of the bad conductors of electricity or non-metals have high resistance.		Most of the good conductors of electricity or metals have low resistance.
3.		Substances with a high resistance are known as insulators and they are used to cover electrical appliances so that the user does not get an electric shock.		They are used as connecting wires of electrical appliances.
4.		Examples: Wood, rubber, glass, plastic etc.		Examples: Copper, silver, platinum etc.