1. What is short circuit? What is the common cause of unintentional short circuits in electrical devices?

A short circuit (sometimes abbreviated to short or s/c) allows a charge to flow along a different path from the one intended.
;->is an accidental low-resistance connection between two nodes of an electrical circuit that are meant to be at different voltages

2. What is a fuse? What happens when you blow a fuse?

Fuse is a piece of metal which has a low meltig point and is enclosed in a fireproof case.It is in series with the line.It is always placed before any of the devices it is to protect.This makes the current pass through the fuse before the current goes to the external circuit.
When there is an excessive current because of overloading,the fuse "blows out" and the circuit is broken.

3-a. How do Circuit breakers Work?

A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit.Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city.

3-b. When is there an overload in a circuit?

.An electrical overload is a situation where the wiring to or within a machine or system is subjected to a greater electric current load than it was designed to carry, leading to excessive heating of the wires and a possibility of fire. This excessive current load can be a result of electrical insulation failure (a short circuit) or human error.In an electrical overload, it leads to excessive heating of the wires and a possibility of fire.

6. Why will too many electrical devices operating at one time often blow a fuse?

In an electrical overload, it leads to excessive heating of the wires and a possibility of fire.
In a short circuit, an accidental low-resistance connection between two nodes of an electrical circuit that are meant to be at different voltages. This results in an excessive electric current limited only by the Thevenin equivalent resistance of the rest of the network and potentially causes circuit damage, overheating, fire or explosion. Although usually the result of a fault, there are cases where short circuits are caused intentionally, for example, for the purpose of voltage-sensing crowbar circuit protectors.

7. What are the danges of short circuit and overload?

A short circuit-occurs when conductors of opposite polarity are accidentally bridged by a conductive object or bridged to grounded metal. Metal screwdrivers, wrenches, fish tapes, test instruments, etc. have all been found to have made inadvertent contact while persons were working on live equipment. An arcing fault may be established that is limited only by the total impedance of the circuit. The arcing will continue until circuit breaker, fuse, or equipment ground fault protection device on the line side of the fault opens the circuit. Even if the short circuit protective device opens the circuit without any intentional delay, portions of the conductors and other metallic materials in the path of the arc may explode violently, showering the area with hot molten metal that can cause severe burns or death. The flash associated with the arc can also cause permanent eye damage. Finally, a short circuit may expel shrapnel toward the workman, penetrating clothing or the body.
Overload-leading to excessive heating of the wires and a possibility of fire. This excessive current load can be a result of electrical insulation failure ( a short circuit) or human error.