Abhishek Chandra Solutions for Chapter: Electricity, Exercise 4: EXERCISE

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

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 is passed through the conductor for double the time, the heat generated will become

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

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?

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?

The electric power consumed by a device may be calculated by using either of the two expressions: $P=I^{2}R$ or $P=\frac{V^2}{R}$. The first expression indicates that the power is inversely proportional to $R$, whereas the second expression indicates that the power is inversely proportional to $R$. How can the seemingly different dependence of $P$ on $R$ in these expressions be explained?

Two electric bulbs $60 \mathrm{W}, 220 \mathrm{V}$ and $100 \mathrm{W}, 220 \mathrm{V}$ are connected in series to a $440 \mathrm{V}$ mains supply. Which of the given bulbs will fuse? Discuss the situation when the bulbs are connected in parallel.