Current Electricity Test - 19

Kirchhoff's junction rule is an application of the principle of conservation of electric charge: current is flow of charge per time, and if current is constant, that which flows into a point in a circuit must equal that which flows out of it.

The resistance of an ideal ammeter is zero. Although, practically it is not possible to have zero resistance of an ammeter.

If ammeter has zero resistance there will be no voltage drop across the ammeter and that time it will measure the most accurate value of current in circuit.

Hence, specific resistance is a property of a material and it will increase with the increase of temperature, but will not vary with the dimensions (length, cross-section) of the conductor.

In a conductor when there is an electric field flowing, there is flow of electrons from one position to the another, this electrons possess a certain velocity known as drift velocity and the relation between the  applied field and drift velocity is given as:

V_d ∝ E

From the above equations, we have found that V_d ∝ E

Therefore, Electric field is proportional to the drift velocity.

N is the number of electrons that are moving from one point to another.

A is the area where the flow takes place.

Heating coils are commonly made up of metal alloys which are a combination of two or more elements. The most commonly used metal alloy is “Nichrome”. Nichrome is an alloy of nickel (80%) and chromium (20%).