PHYSICS [1 Mark Question Answer]

The main hazards of working with electricity are: electric shock and burns from contact with live parts. keep electrical equipment dry and away from water prevents damage to appliances and can protect against personal injury and electrocution.

The household electrical energy or the electricity bill is calculated on the basis of the number of kilowatt-hours (kWh) used. One kilowatt-hour is also simply called ‘one unit’.

The live wire carries current from the source to the device (load), while the neutral wire is for the return path of the current from device (load) to the source. The earth wire passes the current to the earth.

Earthing is defined as “the process in which the instantaneous discharge of the electrical energy takes place by transferring charges directly to the earth through low resistance wire.” Earthing is used to protect you from an electric shock.

Miniature Circuit Breaker is a safety accessory with an electro-mechanical mechanism of action. The fuse breaks the circuit if a fault in an appliance causes too much current flow.

An electrical fuse is a low melting point copper or other metal wire that breaks due to heat caused by overvoltage or high load to avoid short circuit or failure to the device. A fuse is an electrical safety device that has the capability to protect an electric circuit from excessive electric current.

The internal resistance of the battery will be equal to the sum of the internal resistance of the individual cells.

A battery is a device that converts chemical energy contained within its active materials directly into electric energy by means of an electrochemical oxidation-reduction (redox) reaction. The overall emf of the battery is the algebraic sum of all individual cells connected in series.

Double insulation protects the user of the appliance from an electrical shock by preventing any possibility of the enteral casing becoming live ( the live wire can not touch the casing even if wires inside become loose), thus eliminating the need for an earth connection.

Inside the house earth wire is connected to input terminal of kWh meter​

After getting a large amount of electrons, the potential of the earth decreases enormously.

While using fuse whenever overloading occurs the fuse wire melts and it has to be replaced to complete the circuit. These days maniature circuits breakers (MCBs) are switches that turn off automatically when there is an overload or a short circuit.

In series connection of cells, negative terminals of all cells are connected to one point and positive terminals of all cells to other point.