Voltage Current Capacitance SAQ

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What is the physical significance of potential difference between two points?

It is the work done in moving a charge of one coulomb from one point to the other.

What is the SI unit of potential difference?

Volt (V)

What is the term used to describe the potential difference between a point and the earth?

Potential of that point

How is a voltmeter connected to measure the potential difference across a component?

In parallel with the component Signup and view all the answers

What is the formula that relates voltage, work, and charge?

V = W/Q Signup and view all the answers

What is the primary function of a source of electromotive force?

To convert chemical, mechanical, or other forms of energy into electrical energy Signup and view all the answers

In a primary cell, what is the purpose of the electrodes and electrolyte?

To facilitate the conversion of chemical energy to electrical potential energy Signup and view all the answers

How does a thermocouple generate a small emf?

By maintaining two junctions at different temperatures, causing a small electrical current to flow Signup and view all the answers

What is the role of a primary cell in an electrical circuit?

To provide a voltage source, allowing electrons to flow Signup and view all the answers

What is the fundamental difference between a primary cell and a thermocouple?

The method of energy conversion: chemical energy in a primary cell versus thermal energy in a thermocouple Signup and view all the answers

What is the relationship between the charge on a capacitor and the potential difference applied across it?

The charge on a capacitor is directly proportional to the potential difference applied across it, i.e., Q ∝ V or Q = CV. Signup and view all the answers

What is the purpose of a capacitor in an electrical circuit?

A capacitor is an electrical device capable of storing electric charge. Signup and view all the answers

What type of current does a capacitor conduct?

A capacitor conducts alternating current (a.c.) but not direct current (d.c.) Signup and view all the answers

What is the SI unit of capacitance?

The SI unit of capacitance is farad (F). Signup and view all the answers

What is the unit of capacitance?

The farad (F) Signup and view all the answers

What is the purpose of a capacitor in devices such as camera flashes and touchscreens?

The purpose of a capacitor in such devices is to store electric charge. Signup and view all the answers

Why is the constant C, known as capacitance, a scalar quantity?

The constant C is a scalar quantity because it is a ratio of the charge on a capacitor to the potential difference applied across it. Signup and view all the answers

How is the charge on a capacitor related to the potential difference applied across it?

The charge on a capacitor is directly proportional to the potential difference applied across it, mathematically represented as Q = CV. Signup and view all the answers

What is the purpose of the dielectric in a parallel plate capacitor?

to separate the metal plates and provide insulation Signup and view all the answers

What is the formula for the energy stored in a capacitor?

W = 1/2 CV^2; The energy stored in a capacitor is equal to the work done by the battery to charge it, and is proportional to the square of the voltage and the capacitance. Signup and view all the answers

What is the relationship between the capacitance of a parallel plate capacitor and its physical dimensions?

C = εA/d; The capacitance is directly proportional to the permittivity and the common area of the plates, and inversely proportional to the distance between them. Signup and view all the answers

What is the effect of increasing the distance between the plates of a parallel plate capacitor on its capacitance?

The capacitance decreases as the distance between the plates increases. Signup and view all the answers

What is the physical significance of the permittivity (ε) in a parallel plate capacitor?

The permittivity represents the ability of the dielectric material to store electric energy, and is a measure of the material's resistance to electric field. Signup and view all the answers

What is the physical quantity that electric current is a measure of?

flow of electric charge Signup and view all the answers

What is the formula that relates charge, current, and time?

Q = It Signup and view all the answers

What are the multiple effects of electric currents?

chemical, magnetic, and heating effects Signup and view all the answers

What is the device used to measure electric current?

ammeter Signup and view all the answers

What is the unit of electric current in the International System of Units (SI)?

ampere (A) Signup and view all the answers

What is the relationship between the power produced in an electrical circuit and the current flowing through it, according to Joule's Law?

The power produced is proportional to the square of the current. Signup and view all the answers

What is the effect of increasing the resistance of a part of an electrical circuit on the heat production, according to Joule's Law?

The heat production increases. Signup and view all the answers

What is the physical significance of the work done in an electrical circuit, as expressed by Joule's Law?

It represents the heat energy produced in the circuit. Signup and view all the answers

What is the relationship between the time of flow of current and the work done in an electrical circuit, according to Joule's Law?

The work done is proportional to the time of flow of current. Signup and view all the answers

What is the significance of the square of the current in Joule's Law?

It indicates that the power produced increases rapidly with increasing current. Signup and view all the answers

What is the primary function of an RCD, and how does it prevent electric shock or fire?

RCDs (Residual Current Devices) are trip switches that quickly cut off the current when a fault in an appliance causes a small current to flow to earth, thus preventing electrocution or fire. Signup and view all the answers

What is the unit of energy used by the ESB, and how is it defined?

1 kilowatt-hour (kWh) is the unit of energy used by the ESB, and it is the amount of energy used by a 1,000-watt appliance in 1 hour. Signup and view all the answers

What is the purpose of an MCB, and how does it prevent electrical hazards?

MCBs (Miniature Circuit Breakers) are used as safety devices to prevent electrocution or fire by preventing too large a current from flowing in the circuit. Signup and view all the answers

How do RCDs and MCBs differ in their function and application?

RCDs are designed to detect and interrupt earth fault currents, while MCBs are designed to detect and interrupt overcurrents. RCDs prevent electric shock, while MCBs prevent electrical fires. Signup and view all the answers

What is the importance of using safety devices like RCDs and MCBs in electrical circuits?

Safety devices like RCDs and MCBs are crucial in preventing electrical hazards, such as electrocution and fire, by quickly detecting and interrupting fault currents. Signup and view all the answers