Physics: Heating Effect of Electric Current

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Questions and Answers

What is the heat produced in a conductor due to the flow of electric current called?

Faraday's heating

Ohm's heating

Electrical heating

Joule heating (correct)

What is the relationship between the heat produced (H) in a resistor, the current (I), the resistance (R), and the time (t) for which the current flows?

H is directly proportional to I, R, and t.

H is inversely proportional to I², R, and t.

H is directly proportional to I² and R, and directly proportional to t.

H is directly proportional to I² and t, and inversely proportional to R. (correct)

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

To protect the circuit from excessive current (correct)

To convert electrical energy to light

To increase the current flow

To store electrical energy

What is the material commonly used in fuse wires?

Copper Signup and view all the answers

What is electric power defined as?

The rate at which electrical energy is consumed or dissipated. Signup and view all the answers

What is the SI unit of power?

Watt Signup and view all the answers

What is the equation that represents electric power (P) in terms of potential difference (V) and current (I)?

P = VI Signup and view all the answers

A current of 2 A flows through a 10 Ω resistor. What is the potential difference across the resistor?

20 V Signup and view all the answers

A wire of resistance R is cut into three equal pieces. What is the resistance of each piece?

R/3 Signup and view all the answers

What is the heat generated when a current of 5 A flows through a resistor of 10 Ω for 1 minute?

15000 J Signup and view all the answers

Why is it dangerous to touch an electrical appliance with wet hands?

Water is a good conductor of electricity, increasing the risk of electric shock. Signup and view all the answers

Why are birds not electrocuted when they sit on high voltage power lines?

They are not part of a complete electric circuit. Signup and view all the answers

Why is it advisable to use electrical appliances with ISI mark?

They meet safety standards and are less likely to cause harm. Signup and view all the answers

Two wires of the same length and material but different cross-sectional areas are connected to the same potential difference. Which wire will have a higher current flowing through it?

The wire with the smaller cross-sectional area. Signup and view all the answers

A heater is rated at 1000 W, 220 V. What is the current flowing through it?

0.45 A Signup and view all the answers

When a 4 Ω resistor and a 6 Ω resistor are connected in series, what is the equivalent resistance?

10 Ω Signup and view all the answers

What is the flow of electric charge through a conductor?

Flow of electric charge Signup and view all the answers

What constitutes the flow of charge in metallic wires?

Electrons Signup and view all the answers

What is the SI unit of electric charge?

Coulomb Signup and view all the answers

How is an ammeter connected in a circuit to measure electric current?

Series with the component Signup and view all the answers

What is the relationship between potential difference (V) and current (I) across a conductor according to Ohm's Law?

V is directly proportional to I Signup and view all the answers

What is the quantity that represents the opposition to the flow of current through a conductor?

Resistance Signup and view all the answers

How does the resistance of a conductor vary with its length?

Resistance increases with length Signup and view all the answers

What is the SI unit of resistance?

Ohm Signup and view all the answers

When resistors are connected in series, the current flowing through each resistor is:

Different Signup and view all the answers

The total resistance of two resistors connected in series is:

Equal to the sum of their individual resistances Signup and view all the answers

Study Notes

Heating Effect of Electric Current

Joule heating is the heat produced in a conductor due to the flow of electric current.
The relationship between the heat produced (H), current (I), resistance (R), and time (t) is H ∝ I², R, and t.
The purpose of a fuse in an electrical circuit is to protect the circuit from excessive current.
Fuse wires are commonly made of copper.

Electric Power

Electric power is the rate at which electrical energy is consumed or dissipated.
The SI unit of power is Watt (W).
Electric power (P) can be represented as P = VI, where V is the potential difference and I is the current.
The commercial unit of electrical energy is Kilowatt-hour (kWh).

Numerical Problems

The potential difference across a resistor can be calculated using Ohm's Law: V = IR.
Electric current can be calculated using the formula: I = P/V, where P is the power and V is the potential difference.
The equivalent resistance of resistors connected in series is the sum of their individual resistances.
The equivalent resistance of resistors connected in parallel is less than the smallest individual resistance.

Conceptual Understanding

It is dangerous to touch an electrical appliance with wet hands because water is a good conductor of electricity, increasing the risk of electric shock.
Birds are not electrocuted when they sit on high voltage power lines because they are not part of a complete electric circuit.
It is advisable to use electrical appliances with ISI mark because they meet safety standards and are less likely to cause harm.
A wire with a smaller cross-sectional area will have a higher current flowing through it when connected to the same potential difference.

Electric Current and Circuits

Electric current is the flow of electric charge through a conductor.
The flow of charge in metallic wires is constituted by electrons.
An electric circuit is a continuous and closed path of electric current.
The SI unit of electric charge is Coulomb (C).
The SI unit of electric current is Ampere (A).

Electric Potential and Potential Difference

A cell or battery provides the energy to maintain an electric current in a circuit.
The SI unit of electric potential difference is Volt (V).
A voltmeter is connected in parallel across the points where potential difference is to be measured.

Ohm's Law

Ohm's Law states that potential difference (V) is directly proportional to current (I) across a conductor: V ∝ I.
The quantity that represents the opposition to the flow of current through a conductor is resistance.
The SI unit of resistance is Ohm (Ω).

Factors Affecting Resistance

The resistance of a conductor increases with its length.
The resistance of a conductor decreases with its cross-sectional area.
The resistivity of a material is a measure of its ability to resist the flow of electricity.
Copper is the best conductor of electricity.

Resistors in Series and Parallel

When resistors are connected in series, the current flowing through each resistor is the same.
When resistors are connected in parallel, the potential difference across each resistor is the same.
The total resistance of two resistors connected in series is equal to the sum of their individual resistances.
The total resistance of two resistors connected in parallel is less than the smaller individual resistance.

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Quiz on the heating effect of electric current, including Joule heating and its relationship with current, resistance, and time.