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The resistance of a conductor is a measure of its resistance to the flow of electric current. Its inverse is electrical conductance, which measures the ease with which an electric current flows.
- When an electric current flows through a bulb or any conductor, the conductor provides some resistance to the current, which is known as electrical resistance and is indicated by R.
- Every substance has an electrical resistance, which is why conductors emit heat when current flows through them.
- The SI unit of resistance is ohm (Ω).
- The potential difference between the two points in an electric circuit is defined as the amount of work done in transferring a unit of positive charge without acceleration from one point to another along any path between the two points in the electric field.
According to Ohm’s law, the relationship between the potential difference, current, and resistance is given by
V = IR
Where
- V is the potential difference between the two terminals of the conductor
- I is the amount of current flowing through the conductor
- R is the value of resistance of the conductor
Ques. What is a voltmeter?
Ans. A voltmeter is a device that measures the difference in electric potential between two points in an electric circuit. To measure the electric potential difference it is connected in parallel between the two points in an electrical circuit. It generally has a high resistance and draws very little current from the circuit.
Ques. What is the resistance of an ideal voltmeter?
Ans. An ideal voltmeter has an infinite resistance, which prevents current flow from it.
Ques. Define a rheostat.
Ans. A rheostat is an electrical device with two terminals. A rheostat is a variable resistor whose resistance can be changed to change the amount of current flowing through a circuit.
Ques. What is specific resistance?
Ans. The specific resistance is the resistance offered per unit length and unit cross-sectional area when a known amount of voltage is applied.
Ques. Define Ohm’s law.
Ans. According to Ohm’s law, the electric current (I) flowing through a conductor is directly proportional to the potential difference (V) between the two terminals of the conductor provided that all physical conditions like temperature, pressure, etc. remain constant.
Ques. What is the formula of Ohm’s law?
Ans. The Ohm’s law is given by the formula
V = IR
Where
- V is the potential difference between the two terminals of the conductor
- I is the amount of current flowing through the conductor
- R is the value of resistance of the conductor
Ques. Does the resistance depend on the temperature?
Ans. The number density of free electrons in most conductors does not change with temperature, but an increase in temperature increases the amplitude of vibration of the metal's lattice ions. As a result, free electron collisions with ions or atoms while drifting towards the positive end of the conductor become more common, resulting in a decrease in relaxation time. As a result, conductor resistance increases as temperature rises.
Ques. What is the SI unit of the potential difference?
Ans. The SI unit of potential difference is volt (V).
Ques. Define 1 volt.
Ans. One volt is defined as the electric potential between two points on a conducting wire when a one-ampere electric current dissipates one watt of power between those two points.
Ques. What is the unit of resistance?
Ans. The SI unit of resistance is ohm (Ω).
Ques. Define one ohm.
Ans. One ohm is defined as an object's resistance when a current of one ampere flows through an object with a potential difference of one volt.
Ques. What are the various sources of error while performing this experiment?
Ans. The following are the various sources of error:
- It's possible that the instrument screws are loose.
- Lack of thick connecting wires.
- Using a high resistance rheostat.
Ques. Does the resistance depend on the dimensions of the conductor?
Ans. Yes, the resistance of a conductor depends on the dimensions of the conductor. The resistance of a conductor is affected by the cross-sectional area, length, and resistivity of the conductor.
Ques. True or false: The potential difference across the wire varies linearly as the current increases.
Ans. True, according to Ohm's law, the potential difference across an ideal conductor is proportional to the current flowing through it. The resistance R is known as the proportional constant.
Ques. What is the reciprocal of resistivity called?
Ans. The reciprocal of electrical resistivity is electrical conductivity (or specific conductance). It indicates the ability of a substance to conduct electric current.
Ques. Define the conductivity of a conductor.
Ans. The ability with which an electric charge or heat may travel through a substance is measured as conductivity. A conductor is a substance that resists the flow of an electric current or heat energy minimally.
Ques. What are Ohmic and non-ohmic resistances?
Ans. At low temperatures, ohmic resistances are resistances that obey Ohm's law, such as metals such as Cu, Al, and Ag. Non-ohmic resistances are those that do not obey Ohm's law, such as diodes and transistors.
Ques. What is the shape of a Potential difference (V) vs Current (I) graph for a linear resistor?
Ans. The potential difference V vs current I graph for a linear resistor has the shape of a straight line.
Ques. Define current density.
Ans. The amount of charge per unit of time that flows across a unit area of a specified cross-section is referred to as current density.
Ques. Why copper wires are used as connecting wires?
Ans. When used as a connecting wire, copper has an extremely low electrical resistance. It has a good contact surface, is ductile, and is cheap since it is a good electrical conductor. Copper is an excellent electrical conductor; no other metal comes close in terms of electrical conductivity.
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