Science : Ch 12 – Electricity

A short circuit is a low resistance connection between two conductors. With low resistance in the connection a high current is present which delivers a large amount of energy in a short time. Hence during a short circuit, the electric current in the circuit increases heavily.

Three resistors of 2 Ω is required to get 6 Ω because resultant is more than individual so they all must be connected in series.

In parallel combination, the equivalent resistance is smaller than the least resistance used in the circuit.

In order to get the working of heater properly, fused wire of higher rating must be used.

Q = ne and Q = It∴ ne = It

The gap between conduction band and valence band is much greater than conductors which don't allow them to conduct electricity very easily which in result shows greater resistance, so insulators offer infinitely high resistance.

Ohm's law states that the electrical current (I) flowing in an circuit is proportional to the voltage (V) and inversely proportional to the resistance (R). Therefore, if the voltage is increased, the current will increase provided the resistance of the circuit does not change.

Constant temperature makes the resistivity constant which made resistance constant. Constant resistance again made the Ohms law applicable. Thats why Ohms law is applied only at constant temperature. It is like the conditions apply of the law.

A kilowatt-hour is an amount of energy consumed by a machine working at a steady rate of one kilowatt for one hour. As a result, Joule is a SI unit of energy, but Kilowatt-hour is a Commercial unit.