Given: $P = 25W$
$V = 220$ volts
$\therefore$ Current through the lamp $\text{I}=\frac{\text{P}}{\text{V}}=\frac{25}{220}=0.114\text{A}$
Red color band in the color coding of a resistor has the tolerance of $\pm2\%$
Resistance of conductor $\text{RT}=\text{R}\text{o}(1+αΔ\text{T})$ where $α > 0$
Thus resistance of the conductor increases with increase in temperature.
Electrolytic solutions are those that are capable of conducting an electrical current. They are generally ions, in which both positive and negative charges can move. Polymers and thermosets do not conduct electric charge. Electrons are the charge carriers in metallic conductors.
When the battery is discharging, the terminals voltage of the battery is always $≤$ Emf of cell $[∵\text{r}>0]$
$\therefore$ There will always be a difference which is defined to be lost volt.
In wired resistors are mainly produced with alloys, since pure metal has a high temperature co$-$efficient.
Due to alloy temperature co$-$efficient of wire wound resistor is very low.
Therefore it is very less effected by temperature change.
Kirchoff's second law:- According to the law, at a particular junction the charge entering the junction is equal to charge exiting that junction.
$\Rightarrow $ There is no charge accumulated at junction. This is also called as law of conservation of charge.
The carriers of electric current are electrons. The current in a circuit is due to the flow of electrons. Therefore, the direction of the conventional current is opposite to the direction of flow of electrons.
It is rheostat
$\text{EMF}$ of cell can be defined as:
$\rightarrow $ Workdone in taking unit positive charge once round the circuit.
$\rightarrow $ The open circuit voltage of cell.
$\rightarrow $ The terminal voltage when current is zero.
Specific resistance $($ or resistivity $)$ is an intrinsic property of a material i.e. it depends only on the nature of material but not on the dimensions of the conductor. Thus specific resistance remains the same even if the length of the conductor is doubled and its radius is halved.
Thermal Energy developed $=1^2 Rt ($Because in series, current is same$)$
$\frac{\text{Thermal Energy developedin "R"}}{\text{Thermal Energy developedin "2R"}}=\frac{\text{I}^2\text{Rt}}{\text{I}^2(2\text{R})\text{t}}=\frac{1}{2}$
The electric current is a scalar quantity. Laws of ordinary algebra are used to add electric currents and the law of vector algebra are not applicable.
Carbon resistors are made from a mixture of carbon black, clay and resin binder which are pressed and then molded into cylindrical rods by heating. The rods are enclosed in a ceramic or plastic jacket. They are used in circuits of radio receivers, amplifiers, etc.
A non$-$ohmic resistance is a resistance that does not obey $ohm’s$ law. Among the given options, a diode is a non$-$ohmic resistance.
Carbon resistor is difficult to make of having a value less than about $20 \ Ohms$ because they have ability to withstand high energy pulses, when current flow through the carbon composition body conducts the energy. So carbon resistor can be made with a higher resistance.
End error is removed when the known and unknown resistances are interchanged in a Meter Bridge. This additional length has a resistance known as end resistance. So, when an end error arises, it can be removed by interchanging the known and unknown resistances and taking the mean of the resistances determined.
The rate at which energy is drawn from a source of energy when unit current flows through the circuit or device is called $e.m.f.$ It is measured in volts.
Conductivity $\sigma=\frac{1}{\rho }$ Where r is resistivily.
Product of conductity and resistivity $= 1.$
$Þ$ There is no current through $B.$
$Þ$ There is a current through $A$ as long as the charging is not complete.
Constantan is a copper-nickel alloy. Its main feature is its resistivity, which is constant over a wide range of temperatures. Thus it has low temperature coefficient of resistance.that's why it is used for making of standard resistances.
To maintain steady current through the conductor, electromotive force must be provided by the external device to take positive charge from lower potential to higher potential i.e. in the direction opposite to that of the electric field.
The electric power line enters our house through three wires$-$ namely the live wire, the neutral wire and the earth wire. To avoid confusion we follow a colour code for insulating these wires. The red wire is the live wire, and the black wire is neutral. The earth wire is given green plastic insulation. The colour coding of wires is green for earth red for live and black for neutral.
Potentiometer is the more accurate device to measure emf than the other ones such as multimeter or voltmeter. Potentiometer is highly sensitive and thus, even small emfs can be measured using this device. Moreover, potentiometers do not draw current from the circuit during measurements, like voltmeters.
The charge $($Positive$)$ inside the bottery my go from the positive terminal to the negative terminal.
The current that flows from a point at the lower $($negative$)$ potential to a point at higher $($positive$)$ potential is called electronic current. Electronic current is produced by the movement of negatively charged electrons.
By increasing resistance in the primary circuit the $P.G$ of the wire decreases thereby it requires more length to measure the emf of secondary cell.
By increasing the resistance in series circuit we can move balancing point from sixth to eight wire.
Alloys like constantan or manganin are used for making standard resistance coils due to their high resistivity values and very small temperature coefficient.
For metals, the temperature coefficient of resistivity is positive. At lower temperatures, the resistivity of a pure metal increases as a higher power of temperature. So, the answer is copper, which is a metal.
Electromotive Force $\text{(EMF)}$ may be defined as work done per coulomb on the charge.
The resistance of the conductor increases with the rise in temperature. However, substances classified as insulator tends to show opposite behaviour. Carbon is an insulator.
The practical unit of power is horse power $(hp)$. Kilo watt is also another practical unit of power. $1$ kilowatt $= 1000$ watt; $1 hp = 746$ watt. It is usually used in reference to the output of engines or motors.