Electricity Test - 17

In a series circuit, the equivalent resistance is the algebraic sum of the resistances. The current through the circuit can be found from Ohm's law and is equal to the voltage divided by the equivalent resistance. The potential drop across each resistor can be found using Ohm's law.

Hence, the correct option is (B).

Specific resistance $\rho =\frac{RA}{L}$

$\therefore$ SI unit of specific resistance $=\frac{\Omega \times m^2}{m}=\Omega m$

Hence, the correct option is (B).

When charges are at rest and electric current is flowing, then this flow of current is known as Static Electricity.

Hence, the correct option is (D).

The fuse is placed in the live wire just after the 'electricity meter' of the consumer. Fuse wires are generally made of an alloy of tin and lead and have a relatively low melting point.

Hence, the correct option is (A).

Loss of kinetic energy of moving electrons, because it alters the space between them, as well as much of energy, is wasted in moving them.

Hence, the correct option is (B).

When two bulbs of power $60 W$ and $40 W$ are connected in series, then we have to find the power of their combination. where $I$ denotes current passing through the circuit and $R$ denotes the resistance of the bulb. hence, the power of their combination is $100 W$.

Hence, the correct option is (D).

A flow of positive charges gives the same electric current, and has the same effect in a circuit, as an equal flow of negative charges in the opposite direction. since current can be the flow of either positive or negative charges or both, a convention for the direction of current which is independent of the type of charge carriers is needed. The direction of conventional current is arbitrarily defined to be the same as the direction of the flow of positive charges. In metals, which make up the wires and other conductors in most electrical circuits, the positive charges are immobile, and the charge carriers are electrons. Because the electrons carry negative charge, their motion in a metal conductor is in the direction opposite to that of conventional current.

Conventional Current assumes that current flows out of the positive terminal, through the circuit, and into the negative terminal of the source. This was the convention chosen during the discovery of electricity. They were wrong!

Hence, the correct option is (B).

Nichrome: Most resistance wire heating elements use nichrome $\frac{80}{20}$ ($80\%$ nickel, $20\%$ chromium) wire, ribbon, or strip. Nichrome $\frac{80}{20}$ is an ideal material because it has relatively high resistance and forms an adherent layer of chromium oxide when it is heated for the first time.

Hence, the correct option is (B).

The value of $1 KWh$ in joules

The "kilowatt-hour is the unit of energy and is equivalent to '$1 kW$ of power expended' for one hour."

$\text{ Energy}(E)\; (kWh)=\text{Power}(P)\; (kW)\times \text{ Time}\left(T\right)\text{(hour) }$

Joule is the SI unit of energy and is "equal to the 'kinetic energy' of a kilogram mass of an object moving at the speed of one meter per second" Joule is expressed as $kg{m}^2{s}^{-2}$.

$1 kW =1000 J / s$

$1kWh=1000 J/s\times 3600 s$

$1 kWh =3,600,000 J$

or $3.6\times {10}^6$

Hence, the correct option is (B).

When a current flows through a conductor, heat energy generates in the conductor.

The heating effects of electric current depend on three factors:

• The resistance of the conductor. A higher resistance produces more heat.
• The time for which the current flows. The longer the time the amount of heat production is high.
• Higher the current amount of heat generation is also large.

Hence the heating effect produced by an electric current, $I$ through a conductor of resistance, $R$ for a time, $t$ is given by $H=I^{2}Rt$. This equation is Joule's equation of electrical heating.

Hence, the correct option is (C).

The electrical resistance of a wire would be expected to be greater for a longer wire, less for a wire of larger cross-sectional area, and would be expected to depend upon the material out of which the wire is made. Experimentally, the dependence upon these properties is a straightforward one for a wide range of conditions, and the resistance of a wire can be expressed as

$R=\frac{\rho L}{A}$

where $\rho =$ resistivity

$L=$ length

$A=$ cross-sectional area

Hence, the correct option is (D).

Electrical energy is defined as the flow of electric charge.so, there is also a flow of charges in electrical appliance during its operation.

Hence, the correct option is (C).

Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. 

It is the rate of doing work, measured in watts, and represented by the letter $P$. The electric power in watts produced by an electric current $I$ consisting of a charge of $Q$ coulombs every $t$ seconds passing through an electric potential (voltage) difference of $V$ is

$P=$ work done per unit time $=\frac{VQ}{t}=VI$

where,

$Q$ is electric charge in coulombs 

$t$ is time in seconds

$I$ is an electric current in amperes

$V$ is the electric potential or voltage in volts.

Hence, the correct option is (A).

A conductor allows the flow of electrons through itself that produces an electric current. But conductors also resist the flow of electrons to some extent. When electron flow is restricted, some of the energy of electrons is converted to heat energy instead of electrical energy.

Hence, the correct option is (C).

The correct relationship between the heat produced and the electric current flowing is:

$H=I^2\times R\times t joule$

$H=0.24\times I^2\times R\times t calori$.

When the current passing through the wire heat produced in wire is directly proportional to the square of current passing through the wire.

$H$ is directly proportional to $\left(I^2\right)$

The amount of heat produced in a wire is directly proportional to the resistance of wire.

Hence, the correct option is (B).

When two or more resistors are connected in parallel they are mainly up to the same endpoints. The current will divide so it will become less but there will be no effect on the voltage. It is a property of a parallel connection.

Hence, the correct option is (C).

Fuse wire is generally made from an alloy of lead and tin which is high. resistance and low melting point. It is connected in series in electric installation. If a circuit gets accidentally short-circuited, a large current flows, then fuse wire melts away which causes a break in the circuit.

Hence, the correct option is (D).

The resistance of a conductor increases with an increase in temperature because the thermal velocity of the free electrons increases as the temperature increases. This results in an increase in the number of collisions between the free electrons. The resistance of a conductor increases with an increase in temperature because the thermal velocity of the free electrons increases as the temperature increases. This results in an increase in the number of collisions between the free electrons.

Hence, the correct option is (B).

A Rheostat is an electrical instrument used to control current in a circuit by varying the resistance. The resistance can be decreased or increased with the help of a rheostat.

Hence, the correct option is (C).

Electrical energy is consumed by various electrical appliances. This consumed electric energy is measured in terms of $kWh$ (kilo watt hour) for which electricity bills are paid.

Hence, the correct option is (D).

The resistance of a long wire is greater than the resistance of a short wire because electrons collide with more ions as they pass through. The relationship between resistance and wire length is proportional.

Hence, the correct option is (C).

Electric power can be said to be the rate at which energy gets transported to or from a part of an electric circuit. Energy can be delivered by a battery or a circuit element, for instance, a resistor which releases energy as heat. For any element of the circuit, the power equals the difference in voltage across the element which multiplies by the current. If we look at it from Ohm's Law, we see that $V=IR$ here, thus there are other forms of the electric power formula for resistors. We measure power in units of Watts. Moreover, it is important to know that a Watt $=$ Joule per second. $(1 W =1 J/s)$. Therefore:

$P=VI$

Hence, the correct option is (B).