Heating Effect of Electric Current

Name the material used for making filaments of electric bulbs.

An electrician puts a fuse of rating $5 \mathrm{A}$ in that part of a domestic electric circuit in which an electric heater of rating $1.5 \mathrm{kW}, 220 \mathrm{V}$ is operating. What is likely to happen in this case and why? What change, if any, needs to be made?

Two identical immersion rod heaters are to be used to heat water in a large container. Which one of the following arrangements would heat the water faster:

(a) connecting the heaters in series with the mains supply?

(b) connecting the heaters in parallel with the mains supply?

Match the items in Column I to those in Column II.

The amount of heat produced in a conductor is
(a) directly proportional to the square of the current flowing through the conductor.
(b) directly proportional to the resistance of the conductor.
(c) directly proportional to the time for which the current flows through the conductor.
This is known as Joule's law of heating and it can be mathematically represented as:
$H=I^{2}Rt$
where the symbols have their usual meanings.
If the current is passed through the conductor for double the time, the heat generated will become

The amount of heat produced in a conductor is

(a) Directly proportional to the square of the current flowing through the conductor

(b) Directly proportional to the resistance of the conductor

(c) Directly proportional to the time for which the current flows through the conductor

This is known as Joule's law of heating and it can be mathematically represented as:

$H=I^{2}Rt$

where the symbols have their usual meanings.

Keeping the current constant, the resistance is doubled. The heat generated will become

The amount of heat produced in a conductor is

(a) directly proportional to the square of the current flowing through the conductor

(b) directly proportional to the resistance of the conductor

(c) directly proportional to the time for which the current flows through the conductor

This is known as Joule's law of heating and it can be mathematically represented as:

$H=I^{2}Rt$

where the symbols have their usual meanings.

If the current in the conductor is quadrupled, the heat generated in the conductor will become

More heat will be produced by a given current when two resistances are connected in parallel than when they are connected in series.

All appliances that run on electricity do not convert all the electrical energy into heat energy.

The connecting cord of an electric heater glows while its heating element does not.

An electric fuse works on the chemical effect of current.

The heating elements of electric heating devices are usually made of tungsten.

For the same battery, heating of wire will _____ (increase/decrease) if its resistance is increased.

$1 \mathrm{kWh}=$_____ $\times {10}^6 \mathrm{J}$

Heat generated in a resistor by an electric current will become _____ times if the magnitude of current is doubled.

A fuse wire is connected in _____ (series/parallel) with a group of appliances and/or a single appliance.

Filament type bulbs are _____ (less/ more) power efficient than tube lights.

A fuse is generally made of a thin metallic wire with _____(low/ high) melting point.

The heating element of electric heaters is made of an alloy rather than a pure metal. Why?

Calculate the resistance of an electric bulb which allows a $10 \mathrm{A}$ current, when connected to a $220 \mathrm{V}$ power source.